That's a very thorough assessment. I don't have the Mobius or the ModFactor, as I use alternatives. But both companies are on my radar for modulation and time-based effects. As you've pointed out, Strymon and Eventide each have their own quirks and advantages.
There seems to be a call for that (as well as user-defined patterns for the PF Harpeggiator). Each time this comes up, I wonder how it could be implemented. The encoder/multi-function footswitch combinations are about tapped out (no pun intended). It's debatable how user-friendly that kind of implementation could end up.
A rewrite of FactorLib is a possibility. A small popup utility to graphically enter a user sequence for each device in the Stompbox line. Pitch / groove / effects in the Harpeggiator (PF), tremolo / "slicing" in the MF, etc. Pie-in-the-sky here, but I'd personally love to have control over those "glide" steps in the Harpeggiator.
I suppose it'd be possible to read an incoming MIDI file (with or without an editor involved). MIDI Note Numbers being read as relative pitches, or notes and rests in a 16-step grid determining a tremolo pattern (or groove pattern). These are all stereo devices, so it may be best to have at least two user-defined patterns available.
That said, there are ways to control the PitchFactor externally, and add user-defined pitch and amplitude patterns right now. Aux switches snapping between sync rates, looping sequences of CC values, MIDI pedalboard switch sequencing, an upstream autopan switching between inputs, etc. A lot of that involves hardware that you don't usually find in a standard rig, but it can be done.