Playing around with my just downloaded BIAB 2011. Cool new features! Shrinking RealTracks will save over 70 GB space on hd!

But after shrinking the RealTracks I got some problems. Biggest one: Frozen Tracks from 2010.5 sound strange with 2011 and shrinked RealTraks. Are there informations inside the ereased files, the frozen 2010-tracks still need to sound in 2011 as good as before?
Should I restore the backuped files?

Ralf