I have a Quilter Pro Block...LOVE it. Used it with my AX8 and a 1X12 last weekend and it KILLED.
Sound tech even commented on how the "little" rig sounds awesome. I often use a head, cab, and 4X12's as well.
Haven't tried it with FX8 yet, however planning on integrating "everything" and having a scalable rig that can easily work for ANY size venue or gig. I have taken my AX8 and the Quilter to fly gigs and no longer worry about backline. I can basically use ANY cab and simply adjust tone via the Quilter controls on the spot, without having to touch the AX8.
The AX8/FX8 combo was something i hadn't thought of, yet makes a ton of sense. I will have to try that as well.
Point is, the little Quilter amps have great options, plenty of headroom, and weigh 4lbs.
For me that is sweet.