Triode versus Ultralinear/Pentode

I'm not so much worried about power, as the Music Reference RM9 SE would be 70 watts in triode - way more than enough for my Merlins, I'm thinking about whether converting an amplifier from ultralinear to triode makes much sense if the amp was not desinged for triode operation from the ground up; I just fell there must be some compromise in this apporach rather than being built and spece'd specifically for triode appplication, like my CAT JL2.

I'm 95% there Tvad. It's why I have doubts over the wisdom of what I am considering. I think your logic is impecable. It's not like Roger said, "great idea, I don't know why I didn't think of that." - Although I'm sure he was also interested in bringing something to market with more power than triode would have provided. The whole triode idea is driven by the fact that my speakers (Merlins) like to be driven by amps with very low damping and NFB, and triode operation theoretically permits use of less NFB (or none?), etc. But I do hear the logic behind what you are saying, and I'm leaving well enough alone and going with the amp as designed by Roger.

Taking up atmasphere's point and changing the question. Is it always true that the compromises envolved in making an amp adjustable between Triode and Pentode, mean they will perform worse than an amp optimised for triode or pentode only?
To answer my question and having spoken to a few tube amp designers, it is my belief, that the compromises do, inevitably, have some effect on performance.