We are currently running an NW6 SP5 infrastructure. We need to milk it a little longer before upgrading/replacing all our branch office servers. We have need to upgrade some DC servers to 6.5 of which we have licensing for. Does anyone see a problem with upgrading our Root server that contains the master replica of all partitions including [Root}, our two servers containing R/W replicas of the [Root], and a few file servers to 6.5; all the while leaving the branch office servers at 6.0 SP5? My plan is to upgrade the root servers first and then the file servers at the DC. Any suggestions?