Thanks for all the comments back (both positive and negative )

Here's the rest of the story:

1) this was not the first screw up of delta, and so it was "the straw" so to speak
2) for those who say "he'll be back" - go ask continental how that's worked out. They screwed up 13 years ago and i only flew them for the first time again this year because they are now part of United so i didn't have much choice (million miler on United means i've made the loyalty/screw up calculations on that airline and found on the whole they are worth it)
3) i wasn't dealing with a gate agent - there weren't any (at both gates) - i was in the sky club dealing with the ticketing person who had no one else in line besides me...
4) i understand restricted capacity due to smaller planes, cancelled flights, IRROPs - i have worked as a consultant for 17 years, and for quite a number of those specifically with airline clients, so I understand and can recognize a "bad day" versus poor customer service.
5) i never lose luggage on AA because (as a consultant) I only travel with carryon.

6) for those who PMd me - i'll send you a note back in the next week or so to work out details for those upgrades, etc

So, yes, Delta is done for me. I was actually a NWA customer (plat) who was migrated to Delta, and frankly have never been very impressed. The only thing i'll miss is the Biscoff cookies - and i can get those from the manufacturer.