The use of a central server shouldn't present too many problems. Those of us that did the original OTA update of Ermine for the EE were presented with a page that required us to agree that we were updating with a beta release and were doing so at our own risk. I assume it was the same for the PE.
The thing the OTA server would need to know is what device is it, EE or PE? Since the old entourage server was able to work that out any new server should also be able to - it might prevent the problems we have been seeing of late with people trying to use the PE update on the EE, prompted, I suspect, by the lure of having the market available.
On a side note - we might even be able to attach to the Russian OTA server
