if OACS plans to move to subverison "eventually" I wouldn't want to move to another rcs "in the meantime." two migrations is worse than one migration. :)
another thing about perforce -- its win32 client is excellent, but other platforms are pretty much stuck with the commandline. (A co-worker of mine tried a TK frontend but was unsatified with it.) I know a lot of the oacs community lives in a unix world by preference so that might not be a good fit. Nothing against command lines of course, but that's something to consider.