Stiffer USD forks (35mm instead of 33mm) disk brakes and an easier time finding parts were the determining factors. hen the new front end is done the swap should be easy.
I think you mean RSU.
And RaceTech does have emulators for the 550 and 750 forks which will make a world of difference.
Check out sohc4.net for plenty of info on rebuilding those forks (and maybe to score a pair cheap off someone doing an upgrade).