Not a problem on the surface, but unfortunately some programs set and use hard-coded paths to determine the location of the roaming profile on the local PC. If a person runs such a program while using a roaming profile on a new install (not an upgrade) of Windows 2000 Professional, the program would save the profile location as Documents and Settings folder. No problem until that person logs into a Windows NT4 workstation and then the program with the hard-coded profile location will not work, or be flaky or ??? The same problem arises going from Windows NT4 to Windows 2000.
The question is which programs use hardcoded paths? Sounds like a land-mine waiting to be stepped on.
A different problem arises because of the access permissions the workstation requires on the server with server-based profiles. An NT workstation, at the end of a session, updates any desktop changes to the users profile file on the server. Its essentially a change of contents. A Windows 2000 workstation does the same PLUS it changes the ACL of the server profile file. Change access permissions to the profile share on an NT4 server is not enough, the Windows 2000 Professional workstation needs WRITE_DAC access to the profile share, achieved by granting Full Control. Without that level of access, you get an access denied message when the user logs off the W2k workstation and it can not update the ACL. When the roaming profile is stored on a W2K server, change access is sufficient for either NT or Professional workstations.
The relevant Microsoft kb articles are: