I've ranted about how hard synchronization is.
Here's confirmation from a former Sync Services engineer: MildMannered Industries - MobileMe. (via Gruber)
Synchronization is hard to get right, and small errors grow with each sync until they become big disasters. It's impressive Exchange/Outlook sync works as well as it does, and the original Palm/Desktop sync success never got the respect it deserved (though Palm wisely kept things as simple as possible).
Apple has never done Sync well. The old .Mac service, and the built-in OS X sync services, have been plagued with problems.
Bottom line -- MobileMe isn't going to be healthy for a long time -- if ever. In particular, email sync makes no sense in the IMAP era.
If you insist on using Apple's sync solutions, be sure you have good backups and a way to restore from backup.