Hey BRX - fully appreciate you have a full Helix and adding an additional separate pedal(s) to that doesn't make sense for you.
But for pretty much everyone who is planning to get an MXR (or FI), they will either be upgrading an existing set up, shift something else off their pedal board to accommodate, or get a bigger pedal board. It's what many of us pedal users do very regularly, when the need arises.
I also completely also get your point re. synth pedal tracking - it's a fundamentally important issue for live use and has been picked up by several of us on this thread. Was precisely the reason for my choosing to go with the Boss SY-200 despite it not having as good synth sounds as several other synth pedals - it's my personal compromise and for me considerably better than the "nothing at all" alternative.