I noticed the problems with green thumb in Halo 2 (and Halo 1?) also, and it really bothered me. I ended up putting everything on universal green thumb, which is serviceable at least, and doesn't leave me pressing the wrong thing when I switch games, except for Halo 3 sometimes because those maps going with RB as action/reload and X as equipment is still ingrained in my brain. The really nice thing that I found is for Halo 3 the layout graphic for it shows crouch twice, and it puts left weapon reload on the left stick click for reasons known only to the guy at Microsoft whose job it is to ruin perfectly good user interfacing.