Just for kicks I loaded RMX 1.5 in Live and compared the CPU useage with RMX in DP 4.6. In both apps I loaded RMX as an AU and used Backbeat
Blues Shuffle as the test patch. I had the sample buffer set to 512 in both apps. In both apps I had two midi tracks of RMX running.I would be interested if anyone has tried this. Here's what I found.

DP w/ RMX- CPU at 25-30%
Live w/RMX- CPU at 10%

I realize that this is not a scientific test by any means, but it is very interesting. It also raises the question whether there might be less CPU hit if you opened RMX within Live, and have Live slaved to DP. Instead of opening RMX within DP. The only way to do this (as far as I know) is to slave Live to DP using the interapplication MIDI within DP. If anyone has done this, please post your results. I'm running a G4 Dual 1.25 w/ 2GB RAM.