Yea, I actually run our current SUS on an older Mac Pro. It provides both Apple software updates and Adobe software updates (for our Adobe deployments) and is dedicated to these two services. My primary server (running Mountain Lion—capable of Mavericks, but again, because of the File Sharing issues in Mavericks Server, we're sticking with ML Server for the time being) is a loaded 2009 Xserve—which I don't run "secondary services" (my term <G>), like SUS, on.
Unfortunately, the current SUS box won't do Mavericks Server (though, I have tested running a VM of Mavericks Server, just for SUS and Caching, inside the physical OS, and it worked fine, but seemed like a waste of system resources and just really didn't make much sense—and a bare metal install doesn't work because of RAID, etc.), so I was considering the Caching Service in ML as an alternative (if it did, in fact, feed Mavericks clients). I realize I could just "turn it on" and see what happens, but would rather look into first (as I assumed others would have ML Caching Service on, and probably had Mavericks clients on the network, so would have the info I was looking for).
Anyway, at this point, unless ML Server Caching Service will do the trick, Reposado it is.
k.