These are some great responses. Its interesting seeing how individuals use this unit in their own situations.
And the quad cortex was another good suggestion for these type of endeavors.
I think in some way, it can also be seen as an option when you feel weird about moving a head you paid an exorbitant amount of money for in and out of local/semi local locations. And so you need to case it up. And at that point you start thinking hmm... how close can I get to this tone with a modeler that fits in a rack so I can just suit case it up and feel less picky about it.
I have noticed if a knob gets bumped on the Herbert, depending which one it is, barely bumping it changes the tone.
Recording.. it seems like a very useful tool.
To answer the actual question... I have had different Fractal units for over 15 years. I still have an Axe II, and an FM3.
I do think they have continued to get better over time in terms of tone and feel. They are pretty much the best digital thing you can get, and whether you prefer it into studio monitors for recording, FRFR for playing, or through a traditional poweramp and cab.
People also forget how powerful they are for effects and routing/switching. You can pretty much do anything you have ever wanted. If you want a switching system with 10 different "pedals" within a W/D/W rig, with 8 different amps.... you can easily do that in a preset. You dont need a room full of shit with 100 feet of cables.
That being said, if you listen critically for specific tones you prefer, you are probably going to find shortcomings compared to a tube rig. It is gonna feel different, or be more fizzy, or be blurrier, or something. A lot of it comes down to how much you are willing to sacrifice for everything you gain, and I also think type of music is a big deal. I think if you play smooth 80s leads, or clean with effects, it is hard to notice. The high gain chunka chunka stuff is harder to get.
For example, I have been loving my Synergy rack lately. I use my Axe II through a parallel mixer for effects. I dont run it straight through because I notice how it changes the dynamics and punch. Someone else might not care if having the routable effects, gate, EQ, etc... is more important, but to me, in Madison Square Bedroom, the smallest things bug me. You will find several posts out there from me talking about how it messes with the Dynamics of tubes. However, that doesn't mean I dont still love my Fractal gear. I have just found I prefer my tube gear to remain analog, and my digital modelers to not combine with tubes.
Overall, you do need to tweak it for your use though. What I do through a tube amp into cabs is very different than how I tweak through monitors. I switch back and forth between my tube stuff and using my FM3 as a complete unit. I do notice feel changes, but I am also neurotic about comparing them, lol. In the end, Fractals are great, but I dont think it is fair to always compare just with your favorite tube amps for one specific thing. The amp will probably win. However, if you compare it as an overall system, there are far more comparable points to consider.