I am running into the same problem as you. What I am sort of doing is storing the database on the server, where it is running as Library/UPnP server. Then, I can open read-only on any HTPC. Now I have auto import disabled but I like it that way because otherwise, new files get added without cover art. My way, I have to manually add the new files (usually remove all video and add back) and then I can fill properties from filename and apply cover art. Then, I just need to restart MC on any HTPCs. If I was running into this a lot I would just setup a batch to close Media Center and start it up again at 4 AM or so every day. That would essentially solve the problem completely.
I just don't add stuff too often and when I do, it's usually a bunch at once. In fact, as far as music goes, I have a stack of CDs sitting on my desk. It's just a hassle to get setup (I scan the cover art) so I do it once in a while and do a lot.