I wish I could say the same!
I've gort an M5, I've yet to explore this expression-pedal implementation because Line6 didn't use a regular TRS input to control it. Finding an expression pedal that actually works with the Line6 is a PITA. I haven't been able to find the Line6 one here locally, ATBH I don't want it as I've heard the plastic is spastic ie not very robust. What else is there that works with it? Mi$$ion? So even if I get an expr pedal that works with my M5, I'll never be able to say it's superb.
This is slightly OT, but I'm pretty sure you can create a simple adaptor that will convert the TRS of any expression pedal to the TS of the M5. Just need to connect the tip and either the ring or the sleeve of the TRS to the two contacts of the TS. Polarity shouldn't matter either, and I'm pretty sure that within a reasonable range the resistance doesn't matter as well.
I'm also pretty sure the "Mission Engineering Line-6 adaptor" does exactly that.



