Further to @Normandel's suggestion about getting the 7DII fixed. I had a look on Canon's recently released (2024-11-01) list of gear no longer serviced, and the 7DII is not on that list. This is confirmed by an article on Petapixel suggesting that your 7DII will be serviced until Jan 2027: This is How Long Canon Will Continue to Repair Your Camera | PetaPixel. In principle, Canon should repair it, although in my location they have declined to accept for repair gear that was shown as still supported, so it pays to check, but the question comes to down as much to the economy of cost to replace a shutter mechanism.
You could decide to stick with the 7DII and pay to repair it, accepting a risk that other components may well fail in the foreseeable future and repair may not be possible, given this camera has been well used and was released 10 years ago. The question is whether the cost of repair is going to be approaching that of a replacement. My colleague Normandel has a great respect and attachment to legacy gear, and I am by no means disdainful of DSLRs - I still own, and shoot with 6 DSLRs myself, so I hope that demonstrates that I am not biased here.
However, you come to a decision that is not just about the cost or viability of repair...
This situation is not new: we saw it with the switch from film to digital and one can find similar significant changes throughout the history of photography as the technology changed - with the resultant dichotomy of reactions between those who like things the way they were and those who want to leverage the new tech. I will happily admit that there are SLR and DSLR cameras that I would never sell because I have a deep attachment to them outside of pure functionality, but for most of my legacy gear I realized the significant advantages that a mirrorless camera can offer in getting the images I want. I had the 7DII and loved it, but mirrorless offered me a better tool with significant benefits.
For me, having a fully articulating LCD screen was a great boon for going high or low, and the ability to see exposure in real time through the viewfinder or LCD is excellent for low light or high contrast scenarios. The focus and eye tracking are (to coin a vastly overused cliché) 'game changers' for wildlife and for sports shooters, where our subjects may be on the move or even obstructed by other animals or vegetation, and Canon makes the best tracking system out there at this time.
However, this is not just a question of moving from the a DSLR to MILC, but also moving from crop-sensor to full-frame. Like anything else, there are pro's and con's here. An APS-C sensor pre-crops the image, offering what seems like a magnifying effect to the Field of View, but like everything else that comes at a cost: in terms of dynamic range and noise because of the smaller photosites. There are inherent benefits to using a full-frame sensor in terms of noise control and dynamic range, and tolerance to low light conditions, but you do lose that magnifying effect. So, much depends on the optics you use - and I can say from experience that the Sigma 150-600c is an excellent lens, so you use it with a FF MILC camera and crop from there.
The degree of cropping you need and the resultant loss of pixels then begs the question of what you are going to produce. Any files for on-line or social media display is going to be massively downsized anyway, so I would not say that is an issue, and I have produced cropped images up to A2 size with no issue. Furthermore, post production software applied to RAW images in particular can work miracles in terms of uprating file sizes, so there are options you can consider: the image is about far more than the camera body.
My point here is that there is much to consider...
I will leave you with a couple of images taken with the R series cameras and the Sigma 150-600c lens, so you can get an idea of what it offers.
This is the Sigma 150-600c used with the demanding R5, which is a 45MP camera that tends to show issues with gear or technique, and has the same focusing system as the R6 and a slightly older one compared to the R8.
Testing the Sigma 150-600 Contemporary with the Ca... - Page 2 - Canon Community
cheers, TREVOR
The mark of good photographer is less what they hold in their hand, it's more what they hold in their head;
"All the variety, all the charm, all the beauty of life is made up of light and shadow", Leo Tolstoy;
"Skill in photography is acquired by practice and not by purchase" Percy W. Harris
