Hi,
No, you don't have to downgrade Java to use REW 3.29. It seems to work just fine and the prefs seem to be the same as REW 4 (default cal files for mic and soundcard etc.).
As far as using virtualization software like Parallels this guy did it and it seemed to work much better!
http://www.hometheatershack.com/foru...-book-pro.html
I did a search for Mac on this forum and found some other interesting tid-bits. All in all it seems like Apple's Java implementation is lacking... and I believe this to be true. Apple's Java has always lagged *way* behind other platforms, especially in speed, since the inception of Java more than 10 years ago. But, hey, I didn't buy a Mac to run Java!
Mace