Well, the email didn't go through anyway - their support page with all it's drop-downs and such netted me repeated hits on the "submit" button with no joy. Stupid coders.
And the phone was an approximate 1 hour wait time.
I called the Garmin store on Michigan Ave, and they said "sure, we can help you out, bring it down..." but before I did that, I wanted to make sure I wasn't being a moron about something. I rebooted the Mac as a PC and ran XP natively, made sure XP knew the GPS was there (even though it was dead, I could still hold down the power and the UP button on the 4-way pad to get it to be visible). It took a few... okay maybe 10 tries, but with the right combination of holding down buttons and letting them go at the proper time, I was able to get it to return to version 3.30. Whew!
I then ran WebUpdater again, and there were no issues. It may well have been some shenanigans with running XP-within-a-window on the Mac, so from now on I'll just boot it up as a Windows box when I have to do software updates. Map transfers go smoothly enough using VMware, though.
Thanks, y'all