Classic is no longer supported after 4.0; all systems would have to be taken to 4.0, converted to SDS, and then upgraded to 4.1 or beyond.
There is an OPS/Enterprise Manager for systems after 4.0, meant for large clusters like yours, but I believe its capabilities are severely less. I believe its meant more for monitoring now then making system wide changes. It obviously doesn't do the sync's anymore either. We don't have any clusters as large as yours, and have eliminated OPS for all our customers that had it. Hopefully Ralph or someone else will have more insight into that part of it for you.