Use native replication. Not only is it supported, but I think you can better integrate or aborb existing pieces (file servers, or systems with appropriate disk space and memory), at a substantially less cost than implementing a DFS system.
My old company tried using DFS, and it was to, put it mildly, an abject failure. DFS (granted it was Windows 2000 based, multi-master) was a crapshoot at best, and when it died so did software delivery.
Also, I haven't heard of Altiris\Symantec changing their position on supporting DFS. I also recall (perhaps not totally correctly) intial support for Cisco's ACNS product, but that quietly went away at some point. I wouldn't discount the need for support by a vendor when considering implementing a management solution.