CP-E is easy to change back. You just have to resolder 1 line. Its not as fast as a plug n play, but then of course you don't have to take your car to a dyno to have it tuned either.
The unichip is undoubtly the most intensive tuning apparatus available for the 6, but no one has yet been willing to pay 800 USD for 10 whp gain...when the CP-E nets you 20 for 550.
I think we'll see the unichip users jump in # once more and more cars become heavily tuned. Things like cams, full exhausts, intake manifolds, custom intakes, built up bottom ends...these type of mods would fully utilize the unichip.
Then of course SCT is still slowly working on the 6 (flasher)...so i think most people are just hoping that comes out sometime in the next 2 years.