Tech 21 cabs contain a Celestion 70/80 speaker and this colour your sound like any cab equipped with this speaker.They certainly aren't FRFR, and you need to switch off cabs in the Profiler.
Thanks for the advice. This is the reason why the Yammy is still my first option. I have read that the Tech 21 pe 60 is less crítical with Pods and Zooms but with the Kemper many rigs will require a cab off choice, so the PE 60 monitor will sound different from the plus cab stereo signal sent to the board.