I have a 2 C-cell and a 3 C-cell Tektite strobe with the zenon lamp modules. The 3 C-cell strobe is rated 30% brighter. They are both depth rated to 500 ft. at least and the package for the 3 C-cell strobe actually says the depth rating is 1000 ft. They are just as compact as a backup light.
I prefer backup dive lights and strobes that use C-cells for their increased power and/or burn time. For limited vis conditions and marking the upline, location of extra stages, etc., you just can't have too much light or effective strobe range. Just think of the problem faced by the Rouses - they couldn't locate their deco bottles on the wreck, and it cost them their lives.
I just wouldn't buy any strobes that use AA batteries.