My understanding is more along the lines of that the PS2 has a lot of power but is insanely hard to program to use it well

This is definitely true. It's way harder to program for according to my programmer friends. I have one friend who solely knows the ins and outs of the sound processors on the PS2 and he is in high demand because he's one of the few that gets it. When we were working on Starfighter he was having to reverse engineer the thing because all the docs were in Japanese. BUT, as far as raw processing power, the GC is still more powerful. I'm told this from the programers that worked on Gladius... which came out on all three consoles simultaneously. Not that it really matters in the end. If the game is fun i could give a flop how it looks most of the time.