First post, and reposting what I wrote on the DoubleTwist forums:
So I gave DT a shot with my Droid X and ultimately gave up and moved to Windows Media Player. It was a painful transition from iTunes / iPhone, and here are some comments:
1. I gave up on DT because the sync duration was just incredibly long. 10 hours and I only transferred about 15 gigs of my music. That said, the transfer did work, it was just too slow.
2. I liked DoubleTwist's iTunes-like UI, and the auto-sync to iTunes.
3. A large portion of my music was in AAC format, so I had a heck of a time converting these to MP3. One Google search solved the problem for me. You can do it within iTunes with a couple settings, select all and Convert to MP3 so it wasn't impossible. I woudl have had to do this anyways as I don't think Android would play an AAC file.
4. WMP sync is in process right now, and appears to be operating at full speed (2 gigs finished in about 20 minutes).
A darn shame as I wished it would have worked. I am not enjoying WMP at all. Good luck and maybe I'll try again in a few months once DT figures things out.
As an overall commentary, I love Verizon and how my droid works as a phone. I drove for 3 hours in rural Illinois and never dropped a call. In nearly every other way I miss my iPhone 4, which I returned after a week.