Well I tried to like FRFR! After going the Yamaha PA speaker route (harsh and "horny" - and not in the best way), I built myself a 2 x 12 full range cab (see pic). It was originally a Marshall 1936 closed back and after doing some research, I removed the speakers and put in two Eminence Beta 12CX Coaxial's with ASD1001 compression drivers. I bi-wired these and powered them from a Crown XLS 1000 which has a 350w output x 2 and an excellent phase correct active crossover function. I tried the new speaker out with some recorded music and the Kemper and the results were encouraging at normal room listening levels. Although I did find I had to adjust for the different character of the sound delivery somewhat and of course balance the level to the HF drivers. With two HF drivers in such close proximity there is some comb filtering apparent with this set up but I find most folks ears compensate for this and it's not really a problem in "real life".
The problem came when using this set up at rehearsal. We are a 5 piece playing classic rock at the usual levels (i.e. pretty loud). No matter how I tried, I couldn't get my guitar to cut through the overall sound. Actually that's not quite true - if I maxed out the Crown to seriously high output levels, I could now hear my guitar. Problem is, the sound was harsh, toppy and quite frankly horrible. After two attempts on different nights I gave up and was disappointed to say the least as I'd spent quite a lot of time and effort constructing the rig. I have been using a Randall RM50 2 x 12 for rehearsals prior to this so this morning I plugged the Kemper into the effects return (monitor out - cab off) and set it up side by side with the FR cab. I set the sound levels approx the same and the difference was night and day. The Randall sounded visceral and muscular with rich harmonics pouring out, whilst the FR cab sounded one dimensional and sterile. Sadly I've come to the conclusion that I'll be sticking to a "real" amp and cab for the foreseeable future as I clearly belong to the trouser flapping brigade. I know I'll be sacrificing some sonic flexibility in this but if the sound is so good then TBH, I don't much care.
Interesting that I seem to be in the minority when rejecting FRFR but just thought I'd chime in with my findings.