Just made the same move last week and had major problems. Finally have the site up, but many key contributors lost their profiles, and all their posts were gone as well. The complaint I got from my programmers is that the code was VERY difficult to work with.
If you have an application called plumtree on your servers, it may conflict with "threads". Also, make sure that you don't have any corrupt files before you begin the transfer. That caused us many problems and we have had to re-install several times.
