I guess it depends on what you want to do with your loops. Rex/Reason is ideal for breaking apart loops for re-sequencing and processing discrete drum hits out of a break, and for re-sequencing and repitching discrete notes/sections of musical loops.
But if you just want full loops straight from your MP3 collection, to layer them up with your own drums or whatever, you don't have to get into all that micro-editing. Just import to WAV on the timeline, or into Kong pads. The chopping and copying may be basic, but no less so than 90s samplers.
One tip that could avoid all the file management and conversion malarkey: use a different soundcard or even separate old computer for your MP3 playing, and record it directly into Reason. Basically treat iTunes or whatever as your turntable.
Last edited by nhsh; 2013-01-27 at 16:52.