It's interesting that you can clearly hear the difference in feel, even though it's someone else playing and it's via Youtube (lack of) sound quality - the real amp has much more dynamics, resonance and 'air' as BF Shred said. (And which if anything the 808 will hinder, not the other way round.) The Axe-FX sounds good - it doesn't seem to have that horrible brittle glassy sound all the other modelers I've heard do - but it still sounds quite linear and not real, somehow. It might sound fine in a finished recorded mix though. I'd also like to hear a comparison with lower gain, more raw overdrive - which is what the modelers seem to struggle most with, rather than the really heavy stuff.