well in my opinion...the rmx has as grainyness that the 480 can't touch...but it's only got a limited amount of uses...
however...the 480 does a LOT more. guess you need both
depends on what you are going to be using it on...personally, i'd take the 480 just on sheer usability (and having two sets of stereo outs helps)
i bet neither of these opinions helps...just my opinion