Portable Home Sync stops on large home directories

We're an advertising shop. We have a fairly high staff to IT ratio, so we rolled out Portable Home Directories over a year ago to simplify the process of implementing new workstations. It's worked wonderfully. Our employees are heavy Mail and ITunes users. As a result, it's not uncommon to have home directories with 20,000, 30,000 or even 50,000 files. We've had an ongoing issue where people with large (in terms of numbers of files) home directories will stop during the sync following a synchronization conflict. They don't crash, the sync just stops and shows the synchronizing dialog indefinitely. It's not always on the same file, and the logs for MirrorAgent don't show any error. If you click "Stop" the login or logout completes normally and the person can work, but obviously that means we don't have current data on the network home. We've been able to resolve the issue by manually copying the files from the local home directory to the network home while the user is logged in, performing a backfround sync of everything but ~/Library and then doing a login/logout sync to sync the full home. Sometimes this process has to be repeated 2 ot 3 times to complete the sync. The issue is we've rolled out several new home directory servers and there are a dozen or so users expereicing the problem. Our current fix is too time consuming to go around doing this by hand, so I'm wondering if anyone out there has had this problem and if you have a more elegant solution. Any guidance would be enormously helpful.