Well, first off, in my direct experience, these extra databases aren’t exactly significant, nor are the user loads that you will experience. Second, it isn’t like we are setting up a permanent resource as-is-where-is. This is just a set of demonstrator databases. It is unlikely that anyone, after playing with any of these, will be particularly attached to the results of playing around adding stuff to one of the DB’s. They can’t really do much in terms of importing data or anything without having any query access.
I think this is a problem that will solve itself. I also thing that deploying new databases should basically consist of using mysql to create 20 users and 20 databases (really, just one user is fine), then just pop in a bunch of /sites directories to support them. When someone needs one, just give them a URL to “Demo13” or whatever.
For QA reporting, I just stand up 100 at a time. No biggie.