Uhm i think that the very simple fact that different people are reviewing the games on different systems might have a liiiiiiiiittle more influence on the scores than how long developers have had tools for, or how good these tools are, or how much electricity the consoles use up...
I know the tendency here is to go super-geek on every subject, but most times the simplest solution really is the most likely to be true...
Just my 2 pennies.
Like is said. There are a few quotes taken from articles that have direct comparisons that lean, somewhat heavily actually, toward the 360 versions of the game.