One thing I think makes a huge difference, and maybe this is just me, but there's a way SIR2 is able to modify IRs to get them just right, and the length can be adjusted. It's called "stretch," and it allows frequencies to resonate longer, so, there's not this fizzy sound (arguably needed), and it has a better feel for me, I just want to play a lot. And that's without any pedals or anything, just pure Eleven Rack and almost any fairly decent IR. I don't know what the Axe FX FEELS like, but I imagine it's something like that. If Logidy ever comes up with a mod button that does that, I'm going back to the Logidy IR loader method for sure.