I own a Quad Cortex. It's a really fun unit. Capturing amps is a really cool feature, thus why I own it (and I only need a small reason to buy a new toy).
I thought about gigging it, and decided against it for a few reasons.
(taking sound quality out of the conversation)
1) It is not even remotely close to the same build quality as a Fractal foot pedal.
2) It gets hot just sitting on my desktop, and it's pitched up on a mesh computer stand, to allow the most optimal cooling.
3) It's buggy - go on FB and look at all of the people who seem to brick the unit - I don't trust it. Does it have something to do with how much tech they packed into this unit (and it not being able to run/cool properly)....I have no idea. All I know is it's not even close to as 'drunk proof' as Fractal products.
If Cliff and team put as much tech (1 DSP) into the FM3 as they thought was appropriate, and it means my unit is more stable - that is exactly what I want. That said - the FM3 sounds better