I've used robocopy also, RichCopy is / was an internal MS only tool. It's mulitple threaded and from the person who told me about it, is a great tool. I don't have a need personally to test it, but thought it was worth passing on since keeping files in sync is a major thing in the IIS planet. I'd be curious to hear your results.
PS - The web-farms I'm working on now are primarily DB driven, so local content isn't a big deal as it has in the past.
Steve Schofield
Windows Server MVP - IIS
http://weblogs.asp.net/steveschofield
http://www.IISLogs.comLog archival solution
Install, Configure, Forget