I agree that VSS is a horrible piece of software but other than the possible database corruption problem, it seems like your situation will be a difficult one to sell people on. For example, you can't say VSS has terrible merge support because, well, you're the only developer. You can't complain about locking checkouts for the same reason. Unless your app is pretty good sized, you can't argue from the suggested 1 GB maximum database size that VSS suggests.
I personally think that in an interview like you're suggesting, you'd be better off looking for lower hanging fruit to suggest like iterative development, TDD or a wiki for documentation. I have fought the good fight to move from VSS to Perforce in an enterprise situation and that was hard enough. I can't imagine trying to convince management of a major source control change on an application that has one developer. YMMV.
