I always "multibox" on USEast3 while testing my stuff. Characters *do not desync* regardless of speed differences. This includes long playing times. I haven't seen anyone else do this properly.
My "multibox" features "no desync", Priests "auto heal" as needed, without wasting MP, some "dancing" features, PROPER mouse broadcasting, and more (potential) features to come with future development.
I've been doing a lot of testing and re-coding because I will be selling Beta access to my software and I want there to be as few problems as possible. PM me if you're interested in participating in the private Beta. Private Beta access is $20 and I won't be releasing if there isn't enough interest.