I've been playing out of old KRK Rokit 5's for about 7 years now; I only play metal and dabble in clean stuff, they've done an ok job and I've had no serious complaints.
A few months ago a friend of mine got his own studio space and I've had the opportunity to try the Axe through a pair of Yamaha HS8's. After about 6 or 7 visits it's clear to me that there's no comparison at adequate volume; the HS8's sound much more powerful and "bigger" overall. I think they're known for being just a tad brittle but this is manageable, Yamaha doesn't pack DSP into their monitors, there's no need, you can just manage any harshness from the axe, or use the filters on the back of each monitor.
A few weeks ago I had the pleasure of speaking with Andy Hunt from Matrix for about an hour (funny enough it was about 5 minutes of speaker talk and 55 minutes of other stuff, really awesome guy) and after that I was set on getting a cab from Matrix, I ordered an FR212A and received it a couple of days ago, and yet again I have to say there's only so much I can compare at adequate volume, it's probably the best full range solution for guitars I've ever heard in my life - class A/B power, extremely loud, extremely clean, powerful, etc.
I'd say that my answer depends on how loud you usually play and what your price range is. It seems to me like a pair of Yamaha HS8's would suit you well; the FR212A is much, much more expensive than a pair of those, and at non-gigging volume, the HS8's are probably a better solution, and can also be used for mixing. I'd be very interested to see what a pair of HS8's sound like with a Yamaha subwoofer... The low end of the HS8's is only as pronounced as you make it, so you can mess with that via the Axe, you get a stereo pair of speakers, etc.
