I promised myself I wouldn't get into this, but hey, it's a Sunday and being England, it's raining .. again, so ...
I'd agree with that last comment, the latest firmware is totally awesome, and if the next release is another step closer, as I suspect it will be, then the differences are becoming very small indeed. AxeFX has come a long way in the last couple of years, with the right gear to play through, it is now very VERY close to the "real thing".
We don't think it's that the Matrix has "solid state tone" as someone suggested earlier, it's that it doesn't have the coloration and distortion of a valve power head, but that part is supposed to come from the AxeFX anyway. We don't see "the Matrix does not sound like a Mesa" as a negative, but rather as a positive thing. As Cliff's modelling gets closer and closer to the "real thing" the overall result is getting more accurate ... the guys using valve heads with power amp sims off are of course missing all these improvements.
If you are running power amp sims ON into a valve head then you are getting a "double processed" sound, you may of course like that sound, but it's not what either Cliff or Matrix set out to achieve, so again, if you are loving the sound, great. It's not what we set out to do though, but it may be perfectly fine for you, if you are loving it, keep doing it, that's perfectly fine by us.
If you are using the distortion in the valve power amp as part of your sound, you will struggle to re-create that sound when it comes to recording direct from the AxeFX, unless you begin mic'ing up the cabs etc, and then we are back to the collection of problems many of us came here to escape in the first place.
We set out to create a neutral sounding power amp, without the harshness typically associated with solid state amps to let the AxeFX shine through. The whole purpose was to let Cliff's modelling work speak for itself, and simply make it louder. We think we achieved that goal, we accept that some people prefer the hybrid tones they are creating with two lots of power amp effects, or by adding a particular color to all their patches, but we believe the place to add to color and distortion is in the AxeFX, not in the downstream chain.
We are confident the GT-FX series amps offer the best choice of a compact, light-weight amplifier that will allow the AxeFX to show it's true capabilities. Given the number of artists now using the AxeFX direct to FOH, with Matrix on stage, we think Cliff is pretty much there, and we are proud to be alongside. If it can work for so many A list artists, it certainly can work for you too. Its a journey towards accurate and flexible tone creation, and we are happy to assist you in that journey by simply making what comes out of the AxeFX louder, if that's what you are searching for.