Dyna Watt switching? I see it mentions Triode operation for 10watts or "dynawatt" for 25watts? I'm guess Dynawatt operation (class a/b still) is different to pentode operation and that switch isn't just a triode/pentode switch.
I'm kind of surprised they went with the EL84, I don't know why but I'd have thought mesa would have gone down the 6V6 route.