I think trade offs abound and these questions are largely unique to each user/use. So I’m not sure I can say anything that you don’t already know but …
Before the H90 I never went direct and used headphones/amp sims modestly. Since the H90 I’m using (stereo) insert mode amp sims all the time and mostly headphones. After trying various things, I settled on a drive, a compressor/eq, and an exciter (all analog) before my H90.
I find the insert functionality/flexibility absurdly useful (simply moving the amp sim in the chain). So I’m comfortable paying what I think of as a latency penalty for it (3.8ms IIRC). But I still have enough latency-anxiety that I decided my only digital pedals will be my H90 and one UAFX amp sim (about 2.3ms of latency). This, in turn, has led me to try to squeeze as much as I can out of my H90. That balance has been a great one for me and it gets better with every new algo b/c the H90 does more.
I also have a three button aux switch and I’m surprised at how much I’m using that. The interplay between the aux and hot switches can be really powerful.
That IRX looks like a great unit and I hear it (1) has midi; and (2) only has about 1ms of latency. If I had one I would definitely ditch the MC6 and control a few IRX presets using H90 program change commands between songs.
Good luck and please let us know what you find works for you and what doesn’t.
