Just my 10 cents..
I ran my KPA through a really nice 2 X 12 cab with V30's for 6 months before finally going for a XITONE Britt FRFR cab.
I'd expected the vast range of profiles to give me wide sonic palette however the cab stamped such a string sonic signature on all of the amp profiles that in some ways it diminished one of the key reasons for buying the thing in the first place (but in no way all of the reasons!).
Once I got the XITONE running then I finally got what I was looking for and I'll never go back. My backline means I know (almost!) exactly what's going to FOH and going direct means no arguing about micing cabs etc etc..
I use MBritt stuff mostly for live however would also point out that Mike pretty much uses the same cab/mics on his profiles so to a certain extent even these through FRFR have some similarity. That's a good thing in my opinion as there's some built-in continuity to my sound as I run through my live rigs (but not enough to detract)
I really noticed the impact of speakers/can/mics/placement on tone when I started to mess with my RZ direct profiles and Tills cablab cabs; up until this point I had no real idea about how significant an influence this is. Sinmix talks about this constantly and he's right!! It also made me realise finally that most amp designs are very similar and I would argue it's the 'feel' of the amp that changes more than the tone between designs..
The long and short for me was that FRFR was the right way and I couldn't be happier.
Si