In chest to head high surf I finally tried the used 6'8" I bought for fifty bucks (then performed some minor repairs with ding dough, added a new leash and nose guard). It was a bit less stable than my 7'2" MiniMal, and a bit tougher to paddle, but once I got the hang of it, I had fun. Even popping up on a big wave and then being dropped nose downward, wiping out, and being spun about underwater was exhilarting.
I can hardly wait till the next time I find good conditions for my 6'8". I'll take my 7'2" out again, to give my burning biceps a rest.