I've had a Helix Rack for a few years now...3 or 4 years, can't remember exactly. It was still a fairly new thing when I got it. It running through my Peavey Classic 50/50 and into a pair of 4x12s (Marshall
or Mesa depending on my mood) was my main rig for a long time. I only recently went back to tubes for my main rig, a Boogie Mark V 35. Although I do plan on eventually integrating the Helix Rack with the Mark and a Revv Generator 7-40 that I have on order.
I also have a Stomp and it's what I use in the truck. Its capable of much more than what I use it for, but it's the best headphone amp I've ever owned.
All that said, if Neural DSP's new piece of hardware is what I think it is, I may end up getting one of those. From one of the tease photos, seems to be in between the HX FX and the Helix, as far as size goes. And in case you've never heard of Neural DSP, they have pretty much the best amp models that you can get. Period. Problem is, they've always been in plugin form. They're supposed to be unveiling it tomorrow. If it's what I think it is, it may take the place of my HX Stomp.