First and foremost Ampeg should edit both the product video and page 4 of the PF 50t owners manual to no longer suggest that the new heads will fit all of the old cabs.
Second they should do something for their loyal customers who own an older cab and also just dropped $900 on a new head. This is my 9th Ampeg purchase, most of the amps and cabs I've bought were new at the time and I've been recommending their gear for almost as long as I've been playing.
I don't see this as a warranty issue. It's closer to a recall issue, where car makers for example do a free retrofit regardless of who the current owner is. I admit the comparison may be a stretch since auto recalls are life, death and liability issues.
Forget requiring proof of purchase. I doubt most original owners of 2012 Portaflex cabs have retained their receipts anyway.
What do I think would be fair?
Either a no charge retro-fit to move or remove the bracing for PF 50t and possibly PF 20t(not sure if they fit or not) owners.
Or a rebate program for people who own the older cabs and want to buy a new one that will fit their new heads. I'm sure Ampeg could survive smaller profit margins on extra sales to people who already own Portaflex cabs and wouldn't have bought a new one otherwise. By their own words it's only a small number of early cabs anyway. I would have been happy if I was offered $100 off a new cab to make up for the misunderstanding.
If the rep on the phone was even slightly apologetic about the misinformation about compatibility I'd have been less pissed off. Many companies would have promised to look into it and possibly clear up a similar issue.
Hopefully this thread will prevent someone from being surprised by this issue. More than half of the bassists I know are on not talkbass and would never read this thread before buying. I won't be the last guy to have this issue.