Okay - I am going to approach this with kid gloves, because it seems everyone gets real hot under the collar when it comes to this topic.
I love my Axe-fx II. It is and incredible product and is probably the most essential piece of gear that I have in my recording set-up in my apartment. Without it, there is no way I could do what I do, because even with an iso box I'm sure the neighbors would be calling the cops on me every few minutes. Further, the tones that I get out of this thing are awesome, awesome, AWESOME! I'm more than happy with the quality of sound that I'm creating with this unit, especially after I compare my home recordings with bands that spent time in a studio recording full rigs, as well as my friends that have actual live recording environments. At first I was a little freaked out about going DI FRFR, but now that I have a good firm grasp of the unit AND
how to dial in the right IRs for the job I'm not even close to looking back.
It's kind of ludicrous to say that because technology moves fast that the Axe-II will be obsolete. If a product does what you want and need it to, even if the next thing comes out, it still keeps doing wonderful things.
Are there differences between the Axe-fx II and tube amps? Here it comes... in my opinion, yes, especially when considering the recording environment. There are, from what I can tell, details that are different from let's say, a tube amp or combination of tube amps which were recorded in a ridiculously expensive recording studio.
If, let's say, money were not an issue, I'd probably be rocking a couple Diezels, a Rectifier, a Plexi or two (Friedman Naked and Brown Eye), a couple Fender Twin Reverbs, my 6505+, a SLO, Fortin Satan (just to name a few), and probably many, many more. I'd then run my small fortune of amps into a series of splitters that would go to all of the boutique true bypass effects pedals that would feed these various front ends and effects loops. Probably three amps at a time would be recorded, each with their own cabinets (which would consist of Mesas, Diezels, Bogner cabs, etc.) that each features a blend of pretty damn expensive dynamic and condenser microphones to record the signal - I mean, just one set of Royer R-121's are about $3,000 after tax and everything...
I'd run these into a pretty damn expensive recording console that features crazy Neve-style preamps and pulteq type EQs until I got the sound that I wanted blended together. Don't forget that these were also recorded in a fantastic space that was treated so as to capture all of the sonic details in my playing, and that each amp may have even had it's own isolated room going on... I'd maybe end up with something that sounds like the following two guitar tones that I haven't quite been able to access with my Axe-fx II:
Tool - Parabola (Guitar Instrumental) - YouTube
A Perfect Circle - Judith (Guitar Track) - YouTube
Keeping in mind, that the issues I may be having dialing in these tones might have more to do with you know... my rather new-ness to to dialing in tones with the Axe-fx II. So, perhaps there are differences in the guitar tones of let's say Adam Jones or Billy Howerdell, who both have a lot more money investment and space to devote to gear, and myself... I'd say I'm pretty damned happy with the tone that I am able to get ouf of my apartment.... recording direct in... via USB... into my Mac...