I'm shocked no one has chimed in with "We have the FM9".
Yes, I tried that. Amazing unit, as is the Axe FX III. But, it was not a replacement for the FX8. The VP4 is awesome, but definitely involves compromise (and yes, it's meant to be a downsized, highly portable multi-fx unit, at which it excels greatly).
I haven't actually done this yet, but apparently, with the FX8, I can run my Ethos Clean Fusion Deluxe in the loop and have full stereo post-fx, along with everything else I need in pre, and with a max of 8 switchable effects.
Plus, scenes are a quick, easy access footswitch press (as is global bypass), with dedicated tap/tempo, and the X/Y is faster than selecting A/B/C/D and completely sufficient. It and the AX8 were extraordinarily well planned and executed units.
Again, still very happy with the awesome VP4, hoping to see this range expand (but please keep the same form and function of the FX8, because it was perfect!).