Sold. Music Rebalance is amazing. A few notes:
- In Preview, with a Pentium G4560 I have to set the buffer (the + sign button next to Bypass) to 5s to have a comfortable margin before playback catches up with processing and you start getting glitches. And that's with the Joint channel algorithm, with Advanced I need even more. The heaviest processing seems to happen if you touch the "Other" stem, for some reason.
- If the bass is too quiet, separation from Other is hit and miss, some times impossible. But if it has a good level, it manages to separate it even when mixed with heavily distorted and bassy guitars (e.g. Joe Bonamassa's Lie
#1 , obviously panning must help a lot here).
- The three separation algorithms do make a substantial difference in terms of quality and CPU. The same goes for Preview vs. rendering. I guess they had to do it this way for Preview to have a chance to work but it's a shame that you can't make adjustments in real time and hear exactly what you will hear when you render. Some back and forth to be expected.
- With a long buffer it takes as long for adjustments to take effect during Preview. At first I was wiggling the sliders like crazy thinking "this isn't working..." Be patient!
Other than that, it's spectacular. Removing or isolating completely one stem (fun to do when you're demoing it!) causes plenty of artifacts, especially with Percussion which gets very "phasey", so don't expect to be able to render the stems separately and remix from there (the dream, right?

), but to make subtle adjustments to balance things better it works beautifully, and even to make a "karaoke" mix to sing/play over, where artifacts and complete removal aren't such an issue.