I've been an Axe Ultra user during two years. It's a great piece of gear, I really liked it, wouldn't say it's like the real thing, but in terms of portability and use in gigs and studio to me was a great solution. The routing posibilities are far beyond VG-99 or KPA.
It's not plug and play at all, you have to spend lot of time tweaking to get the tone you want. I'm as confortable tweaking as playing, but can understand some friends of mine who don't like to tweak at all.
I reached some great tones after hours of equalizing, some CAE superstrat tones:http://soundcloud.com/charles5150/isthislove
Even close into Eddie territory:http://soundcloud.com/charles5150/mean-street
So, you can get nice tones with it you are into spend lot of time on it.
The big BUT came when they announced the AxeFxII, then I realized that I would be in the waiting list during months, and I felt really dependable on it. So, I sold my Ultra in November and got back to the analog world, using a HK Tubemeister and analog pedals for gigs and the VG99 for rehearshalls.
First time I heard about the KPA, I though it was the same convolution thing again. Kind of a "make-your-own-amps" pod. Then, some videos convinced me that it's a different thing, specially the Nasville session one, to me it sounded amazing. And, most important, you don't have to be a sound or IT engineer, it's plug and play.
On the other way, Fractal, who always laughed about profiling, now make the pathetic move to sell customers some thing that appears to be profiling but has nothing to do with it, and they call it "tone-matching". Come on, tone matching is EQ matching, some thing you could do with a lot of DAW plugins around there, it's about compairing two eq curves, and deduce what eq moves you have to apply to the first curve to sound like the second one. I myself applied this technique to get some tones in my Ultra months ago before the II tone-matching.
The truth is YOU DON'T NEED TO BUY AN AXE-II TO DO TONE MATCHING at all. But nowadays the Fractal world is so biased that it doesn't matter what old thing with a new name they come with, or if they call tone-matching or magical-mojo or whatever, they are into buying it eyes ( and ears ) closed.
I'm saving money to buy a Kemper ( it's a click away from any major store, f*** the waiting lists ) and very excited about it. I want to think in terms of melody, harmony and rythmn instead of eq, compressors....