@ How about replication, can it send product updates from one SEPM to another?
Umm... No. Product Updates refer to different versions (11.0.4202, 11.0.5002, 11.0.6000, etc) and they are not replicated and you certainly cannot update one SEPM with a second SEPM. First off, you can *only* replicate between two SEPMs that have the same version.
Content updates (virus defs, IDS sigs, etc) can be replicated between SEPMs. You can also replicate Client Packages (versions)... but these are only for updating the clients.
Sorry if I'm being a little picky about specific terms... it should be clarified.