WHAT PRICE VERSATILITY?
I'm rather in the opposite situation to Rick: I have had both the EF 24-105 f/4 MkI and the new RF version of the same lens, but I don't have the 24-70. I do agree with Rick and Ernie that the EF and RF versions of the 24-70 are highly lauded, however the RF 24-105 f/4 is no slouch and is markedly better IMHO to the EF version.
In the end though, you need to choose the characteristics of the lens that will work for you, and there is more to it than pure image quality, especially if you need versatility. The list of considerations include:
1) What is your budget? Cost can be a big factor, but possibly less so in your case.
2) What kind of photographer are you? Professional, semi-pro, enthusiast, student, casual, purely social - professionals will require the ultimate in performance but will pay for that in cost and extra kit.
3) What subjects do you shoot? Gives an idea of the focal ranges you need - it appears that you want a walk-around unit for a wide range of subjects without other lenses - so that implies a wider focal range.
4) What do you produce? digital media, small prints, large detailed images - the latter require better quality images the former not so much.
5) What are you prepared to carry? In your case, travel suggests reducing weight and bulk, and with a wide focal range without changing lenses.
It would be helpful if, in giving advice, we all say what each of us uses and how we use these lenses, as that is a significant consideration - it speaks to how those factors above are weighted when giving and assessing advice and its applicability to your situation. Speaking for myself, I am in much the same boat as you, EB. I prefer lenses that cover a bit more focal length, find f/4 to be fine, and do a lot of travelling (under normal circumstances). I have a couple of the RF24-105 f/4 units, plus a RF24-240, and find them to be very appropriate for my needs - I find the RF 24-240 is a very underrated lens, and no slouch for it's intended purpose of travel and general photography.
To get a fairly good comparison between it and both versions of the RF24-105, I recommend the following unbiased and detailed review by the respected reviewer Gordon Laing from Camera Labs: HERE, as it shows the 24-240 as no slouch for resolution, and the results about corner resolution are surprisingly to the benefit of the 24-240! There is a second in detail review of the 24-240 from Justin Abbott HERE. Justin Abbott commented on the tracking limitations with the R and RP. I am using the R5 and R6 and their tracking is massively superior to those earlier bodies, a demonstrated by some of the images below.
As regards to image correction: the 24-240 appears to shoot at its widest angle at an actual 21mm, but uses in-camera and post-processing correction to give good results at 24mm. You will not see those issues through the viewfinder: all corrections are done in camera to the display and to the JPGs. PS and LR do corrections to RAW via lens profiles upon loading images. This kind of software image correction is becoming more of a hallmark of lenses, especially those of wider focal ranges and it is effective. Tamron just released the rather amazing XF18-300 for the Fuji X-mount, and it uses similar software corrections to significant effect. The days when super wide zooms rendered very mediocre results are changing in some of the new technology out there.
So, sticking to the theme of versatility, here are some images shot, all hand-held, using the 24-240 at a wide range of locations and conditions to demonstrate the abilities of a lens that concentrates on versatility without losing too much quality yet still show that the lens does an OK job IMHO.. Note that my images have had to be drastically reduced to fit into the 5MP limit for the site, so I recommend that you expand them to full screen size to view.
A local gannet colony - sea mist on the coast. First, at the wide end on the R5, 28mm, f/10, 1/400sec, ISO-200
Fast focus and tracking: Canon EOS R5, 240mm, f/7.1, 1/640sec, ISO-200
Canon EOS R5, 140mm, f/7.1, 1/1600sec, ISO-200
To show images that are more for an urban environment, here are a couple from the celebration of Matariki - the Maori New Year.
Showing no distortions: Canon EOS R6, 24mm, f/5.6, 1/80sec, ISO-400
People photography: Maori Poi Dancer in action: 50mm, f/4, 1/240th sec, ISO-200
Maori Concert Group: R6, 24mm, f/8, 1/200sec, ISO-200
I went to the local museum and shot in very available light the highly-detailed image of a Maori whare, or building - this one is actually for storing food. The light was extremely dim and I had to shoot hand-held.
Canon EOS R6, 61mm, f/5, 1/13sec, ISO-1600
Detail quality: The same image at 100% crop:
Finally, a shot out of my study window of a Pohutukawa shrub, in the garden right outside with a roaring gale blowing - through a slightly grubby double-glazed window.
First the full frame, reduced in size 240mm, f/6.3, 1/400sec, ISO-250
Now the same image at 100% crop. Point of focus was the buds just in front of the bloom
In showing the versatility of this lens, which I am aware you have not considered, I am not trying to discredit the opinions of my respected colleagues, but I am trying to make the point here is that much depends on how and what you are going to shoot, and very much on what you are going to produce. These images, showing the versatility of the range, when not so drastically reduced in size, have been printed effectively 18"x24" without issue and could go bigger if needed.
One thought is that you could keep your EF 24-70, which you acknowledge works well and given you would likely have to pay a hefty upgrade price to get the RF 24-70, instead purchase the RF24-240 for the versatility and have the best of both worlds possibly for the same cost or not much more than getting an RF 24-70.
Comparing the RF 24-105 f/4 with the RF 24-240
I don't have a copy of the RF 24-70, but I do have samples of each of the lenses above, so I decided to try a bit of a comparison of their performance with a series of images of the same subjects, taken from the same vantage points and with the same settings (according to the lens controls). They were both attached to identical R6 bodies, configured in the same way, using Av mode with auto ISO.
This was done in the precinct of my local museum, to test the abilities of the lenses to work within the challenging constraints of enclosed buildings and limited light. Being a museum, tripods are not allowed, so the images are hand-held and thus alignment might not be absolutely perfect. That said, the images provide some interesting comparisons. In all cases, standard lens correction is applied - considering this is done automatically, it seems most aligned with a real-world scenario and is the same methodology applied by DPReview and other lens reviewers.
First both lenses set at 24mm, Portrait of the straight lines of architecture.
Canon Rf 24-105: 24mm, f/6.3, 1/60 sec, ISO-500 
Canon RF 24-240, 24mm, f/6.3, 1/80sec, ISO-250
Comment: the Fields of View are quite similar (thanks to the lens corrections) and generally they look reasonably similar, which is what one would hope for. I found it interesting that the cameras used different shutter speed/ISO combinations for the same aperture. I speculate that this has something to do with the different element configurations of the two lenses. Still, the results seem very similar.
Next a Landscape shot of a display at 24mm
This time, showing elements at close to medium distances and evaluating the colours and tonal values. I must admit I didn't get the vertical alignment quite the same, but the horizontal values are reasonably close.
RF24-105: 24mm, f/6.3, 1/15sec, ISO-1600
RF 24-240, 24mm, f/6.3, 1/4sec, ISO-250
Again there are variations in shutter speed and ISO values, yet the images again appear to be very similar
This is a comparison of images with a focal length of 50mm.
RF 24-105, 50mm, f/6.3, 1/15sec, ISO-1600
RF 24-240, 50mm, f/6.3, 1/2sec, ISO-250
Again, apart from slight compositional variations, the coverage, tonal values are not dissimilar and the corrected lens characteristic are comparable.
Finally at 105 mm (or as close as I could get)
RfF 24-105, 105mm, f/8, 1/40sec, ISO-1600
RF 24-240: 106mm, f/6.3, 1/10sec, ISO-250
I forgot to change the aperture of this last shot, but with a lot more light it is a bit less significant.
SO... that is a rough comparison of the performance of the RF 24-105 f/4 and the RF 24-240 f4.0-6.3.
Comments welcome
