This seems like a well-considered product in some ways, and I like Quilter's solid state tones quite a bit, but there are also a lot of weird choices here that make it feel pretty niche in the end. With the interface, I can't see this appealing to the crowd that is buying a lot of solid state preamp pedals etc because they don't want to use tube amps, but also don't want to go digital, and I can't see it appealing to the crowd that has already embraced digital and this type of workflow. I'm sure the build and fidelity will be rock solid, and the Quilter stuff is head and shoulders above Sansamp in sound imo, but it's truly a shame that this ends up feeling like a product for no one.
I still think it's odd that Quilter haven't put out a power amp pedal. Maybe they have a deal with QSC where they can't do power amp-only products, but with how many guitarists (pro and amateur) buy their amps purely to use as a power amp for modelers or solid state preamp pedals, and the general market for this sort of thing, it seems like an obvious thing, especially if they make a stereo version.