As proof, I saw a guy playing in a local bar that had a killer tone going. I had to see what he was using for a rig. He was using a Boss GT100. I talked to him at his break time. He was running it into the amp's effects return so he wasn't using it's preamp at all. ALL of the sound I was hearing was coming from the GT100, the power amp and the speaker in the amp. His EQ was dialed in perfectly. I was as shocked as anyone when I saw what he was playing through. I gave him some high compliments on his tone and his ability to dial in that Boss unit.
I noticed that I had a typo in my post. This guy was not using a GT100. He was using a GT-10. There is a pretty big difference in these two units. I gigged with a GT-8 for a good hand full of years. I basically just used it for effects. I got all of my drive tones from my amp along with reverb. To hear what this guy did with a GT-10 blew me away. I didn't know you could make one sound that good.
Another one that changed my mind on modelers was a guy in a band named Hyper Static Union. He played a show that I was in the second row for. He had a line 6 Pod kidney bean on the floor by his mic stand. That is what he was running into and that was run into the FOH and monitors. His sound was huge and he had a really good tone. I completely changed my mind on modelers at that moment.
For me the bottom line is that someone who knows what they are doing can make these things sound and feel fantastic to play. I think most people don't understand the units well enough to get there, at least the ones that complain about them. I have been asked to come up on stage and play a few songs quite a bit with friends bands. I have played tube amp rigs that had no feel to them. They were either full on or off. It isn't just a digital thing. It is how you set this stuff up. I have had a few friends tell me that my rig is way more touch sensitive than theirs. This is the first thing that I noticed about the Kemper. I can roll my guitar volume back just a little and it acts like my gigging amp and pedals. I was hooked at that moment. I then profiled my own amp and I can't really see me needing anymore profiles than what I have right now.