I think that this should work fine. I use DFS to replicate files a lot but I have not tried profiles. You should make sure that you have good bandwidth between the two servers so as to not bottleneck the replication or your network, (possible to have own link between each other?). Stating that, I have found this info from plumley on tech republic. His mentions DFS on win2k3 but it should work even better on win2k8 with the new DFRS:
DFS – Roaming Profiles – Known Limits
Starting with the optimum of Windows 2k3 R2, it is really easy and reliable.
1 – Permissions versus Ownership
Roaming Profiles require two things to work and you can set those in Active Directory or Group Policy. To administer the profiles you must take ownership, if you don’t the user owns the directory and you cannot control content or quotas. The user requires modify rights to their directory, not full rights.
2 – Local settings and My Documents
To manage the size of profiles you must separate My Documents by changing the properties. Also set IE to delete Temp files on exit and minimize History. Regular cleanup of ‘cookies’ is highly recommended.
3 – Load times
We have 60 users locally and 10 more in a town 75 miles away. The local users can tolerate profiles up to 80-100 MB. Even with a OC3 line connecting the sites, the remote users find logins painfully slow at 50-60 MB.
(That is why we have a remote server and replicate the profiles.)
4 – DFSR: standards and conventions
Read the MS white papers, then test and test again. Filenames kept to less than 31 characters. Avoid periods and commas in names. The only ‘dot’ (period) sholuld be before the extension and the extension should be normal (.txt or .doc). Path lengths no more than 255 (including filename and extension). Folder depth no more than 8 levels. All of these are standard MS recommendations, not being compliant may not break your system. BUT it makes finding problems much harder.
6 – Older versions of Windows Server have other limitations. I had tried Roaming Profiles in 2000, but had real success when we moved to 2k3.