Well I can't contribute with any fancy statistics but I can tell you that I like Picasso96 because of it's stability and because it was easy to install...
If you want similarities between the two systems, You might take a look at
This search string from aminet... I know it's abit off your needs but SysSpeed2.6 does system speed comparings and you can get plugin-modules from other peoples machinces... This includes some tests with Picasso96 vs CGFX on the same machine this might help you out... :-?
-Otherwise I'll just keep my mouth shut :-)