I had exactly Barry's experience with the upgrade (through David on the forum, rather than P1 support), so I suspect they either have some informal policy about this, or are just giving very fair pricing case by case. If you bought V8 very recently, I'd certainly get in touch with P1 - they're willing to help - two people who didn't like this situation on the forum are very happy with the result.
Multi-select didn't seem to work for me this morning, but it's working now... I'm in the process of upgrading a 60,000+ image catalog, which I fully expect to take a while!
I'll try turning off JPEG editing, but I'm not sure it'll affect visibility (it's not in the import dialog itself that I'm concerned about, but in the catalog). Turning off JPEG editing will certainly eliminate the problem of accidentally editing a JPEG. Using a filter by the raw file extension would work, except that I have three or four types of raw files around (as I'm sure many of us do).