After going through various routing options, I went with placing the HX Stomp in loop 7 on my PBC. Mono in, stereo out. Loops 8-10 are delay and reverb in stereo.
Using send and return on the HX Stomp seemed interesting at first, but you lose 1 of the 6 blocks. I play stereo with two amps and two IRs (highly recommend using IRs), which is already 4 blocks. Plus, the pedal needs to be on all the time, which means you cannot go true bypass if you place the HX Stomp in an insert loop or before the PBC.
I must say, I'm very happy with my setup! I change loop 7 to always on, when using the HX Stomp as amp simulator and already played a few gigs like this. Works perfectly fine with a stereo DI box after my board and got great feedback from the sound engineers. It's also great to show up at a show with public transportation and leave the stage within 5 minutes ;-) When using real amps, I use loop 7 like the other loops and mainly for modulation. I used a Mobius before with "pre" before the PBC and "post" in insert 5-6/7-10. Worked perfectly fine, but I really wanted a solution for an amp sim setup. The Mobius had a decent UniVibe sound, which I missed in the HX Stomp and I also lost the ability to place it before my drives. Enough reasons to buy me a Drybell Vibe machine and boy, this thing is the real deal :-D So much flexibility and you can truly dial in THAT Vibe sound. Works with humbuckers too and the vibrato setting is actually usable! Couldn't be happier. Only other pre effect for me is a Wah, which I use rarely and can always just bring a real Wah and place it before the board. And I'm not even mentioning the possibilities of the HX Stomp on its own...
Now I just need to figure out, how to set up my HX Stomp to change from using amp sims to only effects with keeping the same presets programmed in my PBC. My initial idea is to have snapshot 1 with amp sims and in snapshot 2 turned off. I then only need to change the snapshots on each preset used and save the preset (total up to 10 presets).
Any other ideas?