Doug:
I love my TEC 8/15.5. Cooling is not that much of an issue with the internal fan but it does take about an extra 1/2 hour or so over my TEC6. It's that surface to volume ratio thing. My GM-8 can actually handle it but the G-11 is the way to really go.
They seem to go for about $3400-3800 on the Mart. Which means you can buy NINE (!) of them for the price of the recent AP10.
TEC did make some bigger ones but they seem to be just as rare and shy about showing themselves as the APs.
Having said that, what I would REALLY like to see Roland make is a some nice, light weight, F6, Mak-Newts....now that would be nice.