600EX-RT vs 600EXII-RT

[RobertTheFat]

Can someone provide a synopsis of the difference (if any) between these two speedlites? A side-by-side comparison (on the B&H site) shows no substantive difference except that the "II" model is somewhat more expensive. A couple of the user reviews suggest that the II is easier to use, but don't say why.

[jrhoffman75]

From Imaging Resource:

So what's new? Well the key change is better thermal management, which shows itself in a claimed 1.1x to 1.5x improvement in the number of shots possible in a burst, or as much as a 2x improvement with an optional battery pack. [Note: An earlier version of this item stated that the improvement was in recycle time, based on incorrect info provided in Canon's press release. Apologies for any inconvenience!] And that pack, the CP-E4N Compact Battery Pack is also said to yield increased battery life over the standard AA cells, although we don't yet have specific figures. Another new optional accessory is a set of hard, clip-on type color filters in place of the easily-damaged flexible gels and holder used previously. And Canon tells us that the new strobe also boasts improved weather and dust resistance, although it doesn't provide specific details as to the degree of improvement made. Finally, we're told that the menu system for radio functions has been overhauled for better ease of use, and also now allows you to see the battery level of remote strobes.

[ScottyP]

Still no off-camera 2nd curtain sync, and still no remote adjustment of head zoom, I think?

[ScottyP]

Why would Canon omit these abilities?   Phottix and other 3rd party radio flashes do give them for use on Canon.