I'd had extremely poor luck trying to hotsync, and I'd tried just about everything I could think of to get it to work. Looking at the packet traffic, it seemed that packets were being dropped.

Just for the heck of it, I set up a peer-to-peer (ad hoc) network between my N810 and my Windows machine. Now, I'm not getting 100% success, but close to it.

Edit: Also, I think it helps to use the latest Palm Desktop (6.2) Available from Palm Support.