ratherdashing
Kablamminator
Yep, I got a Kemper. Best of all: I managed to score a used one full of excellent profiles.
Early impression: this thing is the real deal. I have a long history with modellers that ranges from "bleuugrgh" to "hey, that's not bad at all". My home practice & demo rig was Amplitube on my Mac, and it's very nice for that purpose. The Kemper is not "very nice". It doesn't sound like a "close enough" amp rig as most modellers do. It sounds and feels like playing through a real amp mic'd up in a studio.
I emphasize that last point because it is very, very important to understand. The Kemper does not sound like an amp in the room*. It's not supposed to. It mimics an entire recording chain: pedals, amp, cab, microphone(s), mic preamp(s), and post-amp effects. To be completely fair, this is really what every modeller since the beginning of modellers has been doing. The Kemper just does it way, way more convincingly than any other modeller I've tried, and you can work with every part of it in a completely straight-forward, intuitive manner. It truly sounds AND feels like playing through a mic'd amp. Believe the hype.
This is an interesting thing to think about. When you listen to Van Halen I, Led Zeppelin IV, Appetite for Destruction, or any other record, you are hearing a mic'd amp tone. When you listen to a band live in anything larger than a mid-sized club, you are hearing a mic'd amp tone. With very few exceptions, the only time you get to hear an amp-in-the-room tone is when you're playing through your own amp in your own room.
I started off using the built in profiles at my home studio. It was the most fun, best sounding guitar experience I've ever had at home. I then rented/borrowed some recording gear, found a place I could crank my Mark V half stack, and did half a dozen or so profiles of it. I had a friend help me do a Pepsi Challenge with the real amp and the profiles, and on the few times I could even perceive a difference I got it wrong.
The real test was bringing it to rehearsal with the band last night. I ran it straight into the PA. At first it was a bit disorienting because I've spent the past 20 years getting used to an ultra-loud sound cannon blasting guitar at me from one side of the room. After I got accustomed to hearing myself at perfect volume and identical tone (i.e. no treble beam of death or weird volume sink-holes) in every part of the room, I grew to love it. The band was amazed that I was still getting all my usual tones through this rig. To top it off, my set-up/tear-down time was next to nothing.
I have only scratched the surface of what this thing can do. I've only barely tested out the effects and all the crazy ways you can tweak a profile, and I haven't yet done any "serious" recording with it. I'll post more as I go.
If an amp-in-the-room tone is the only thing that does it for you, stick with your tube amp - you'll be much happier.
If, however, you are comfortable with a mic'd amp tone, the ONLY kind of tone you've ever heard from a famous pro guitarist**, I wager the Kemper will make you very happy.
* you can disable cab modelling and send it to a power amp + guitar cab, in which case it will sound pretty much like an amp in a room, but not like any amp that exists in reality.
** unless you are a famous pro guitarist, or are best buds with one
Early impression: this thing is the real deal. I have a long history with modellers that ranges from "bleuugrgh" to "hey, that's not bad at all". My home practice & demo rig was Amplitube on my Mac, and it's very nice for that purpose. The Kemper is not "very nice". It doesn't sound like a "close enough" amp rig as most modellers do. It sounds and feels like playing through a real amp mic'd up in a studio.
I emphasize that last point because it is very, very important to understand. The Kemper does not sound like an amp in the room*. It's not supposed to. It mimics an entire recording chain: pedals, amp, cab, microphone(s), mic preamp(s), and post-amp effects. To be completely fair, this is really what every modeller since the beginning of modellers has been doing. The Kemper just does it way, way more convincingly than any other modeller I've tried, and you can work with every part of it in a completely straight-forward, intuitive manner. It truly sounds AND feels like playing through a mic'd amp. Believe the hype.
This is an interesting thing to think about. When you listen to Van Halen I, Led Zeppelin IV, Appetite for Destruction, or any other record, you are hearing a mic'd amp tone. When you listen to a band live in anything larger than a mid-sized club, you are hearing a mic'd amp tone. With very few exceptions, the only time you get to hear an amp-in-the-room tone is when you're playing through your own amp in your own room.
I started off using the built in profiles at my home studio. It was the most fun, best sounding guitar experience I've ever had at home. I then rented/borrowed some recording gear, found a place I could crank my Mark V half stack, and did half a dozen or so profiles of it. I had a friend help me do a Pepsi Challenge with the real amp and the profiles, and on the few times I could even perceive a difference I got it wrong.
The real test was bringing it to rehearsal with the band last night. I ran it straight into the PA. At first it was a bit disorienting because I've spent the past 20 years getting used to an ultra-loud sound cannon blasting guitar at me from one side of the room. After I got accustomed to hearing myself at perfect volume and identical tone (i.e. no treble beam of death or weird volume sink-holes) in every part of the room, I grew to love it. The band was amazed that I was still getting all my usual tones through this rig. To top it off, my set-up/tear-down time was next to nothing.
I have only scratched the surface of what this thing can do. I've only barely tested out the effects and all the crazy ways you can tweak a profile, and I haven't yet done any "serious" recording with it. I'll post more as I go.
If an amp-in-the-room tone is the only thing that does it for you, stick with your tube amp - you'll be much happier.
If, however, you are comfortable with a mic'd amp tone, the ONLY kind of tone you've ever heard from a famous pro guitarist**, I wager the Kemper will make you very happy.
* you can disable cab modelling and send it to a power amp + guitar cab, in which case it will sound pretty much like an amp in a room, but not like any amp that exists in reality.
** unless you are a famous pro guitarist, or are best buds with one
that sounds perfect for your gig rehearsals and recordings, congrats! 
I would love to get one or the axefx2 but need to save up for like 5 years or so...
As you said, it's the recorded tone, it has to fit in your mix. I don't say that the Kemper sucks, it's just that it didn't suit my workflow. If I had mic'd amps I wanted to profile, then I'd absolutely grab one. As it is, I run amps into the computer via the FX loop and add power amps and cabs via software.