Well, I got my free copy of VistaDB 2.1 for .NET.
So far, so good. Installs cleanly enough.
Managed to whip out a .NET test app in no time.
Will definitely be considering VistaDB for the .NET Version of PSQ
I've done some searching to try and find an independent review of VistaDB. If anybody knows of a thorough evaluation please leave a comment.