Every time I need reassurance, I go youtube, search for amp demos and then compare with what I can achieve with the axe. I listen for details through my monitor headphones.
Most of the time I hear that I can achieve tones on, what I think is, the exact same level of quality, so I am most definitely reassured. I can't talk about feel as I don't know how a real tube amp is supposed to feel, but the sound, to me, is definitely there.
But sometimes - I feel like it's maybe a bit lacking. Dunno whether it's the cab IR's or the amp modelling, the guitar, the player, or simply a false impression. I believe that the axe is very good at producing modern polished tones, but maybe lacking in more vintagie raw tones? As I've worded that once - "Maybe the Axe FX sounds too perfect?". I was accused of being stupid for not liking perfection and was told to get a Line 6, when I said that on the forums...
Here's an example of a raw tone: