Bob, I would not like to attend a talk on fighting bettas. I am deeply opposed to fighting animals of any kind.
Since I love you I've decided not to picket your house for thinking about it.
I think we all know that fish don't have mammallian emotions but it's easier to refer to what they do have in terms like, "angry,happy,sad" and such.
I think that's very, very interesting that you're keeping them together Sue, gives me the urge to try it.
I think Betta's are happier in larger spaces with things to do and look at. I think they like company of sorts also. One of my bettas had a 12 gallon tank and a few small fish companions for about a year. He was happy and active. Then one day I noticed he had grown "depressed". He stayed in his hidey place and only came out when I came to the tank and interacted with him. I tried everything, changing his decor and such to perk him up.
Finally I divided the tank and got another betta for the other side.
That was the trick, he's been a busy, active betta ever since! He's a Petco betta by the way and I've had him for 2years and 4 months.
I have a betta from Sue that I got at the show. I'm not sure how old he is or how long he had been jarred but when I got him he went into a 2.5g with a little filter. At first he was pretty put off with the whole situation. Like he just didn't know what to do with himself. He also swam a bit weakly when it came to dealing with the current.
He eventully got used to it though and just recently moved into a 10g with a few other small fish and apple snails. He appears to be perfectly delighted and handles the current quite well now. The only problem I had was the background. I had a glossy deep blue background on the tank when he went in and he could see his reflection, he spent the first two days trying to kick his own butt.

He was so intent about it I couldn't even distract him. I finally took the background off for fear he was going to exhaust himself. Besides...I wanted him to pay attention to me!
Now I mirror him every day so he gets to flare and show off but it's in moderation,lol!
I don't think they are necessarily unhappy in small containers. If they don't know the difference what's to be unhappy about? As long as they can move a little and are well cared for it's okay. It's necessary if you're breeding and keeping a whole lot of them. Sue had mentioned to me though that she makes sure they each have a companion they can see next to them to keep them entertained.