With the updates to the mp-201 it seems as though the cv mod for the phatty is unnecessary, as the 201 can provide multiple pitch, and modulation cv, without having to send the phatty to the factory. Is there any benefit to having the cv mod over the mp-201?
No AD/DA convertion involved with going from MIDI OUT LP to MIDI In MP to CV OUT of MP to CV In of X, no extra pedal to find a place for, and obviously the LFO signal from LP is not available from the MP either, albeit you could probably match speeds closely enough.
THe MP201 is somewhat more expensive than the Phatty CV mod.
Digital conversions kind of scare me, but if there is no audible stepping then it is ok with me. also i assume the multi pedal uses the same method to produce voltages as the phatty, thus the phatty cv has just as much AD/DA conversion, however i may be wrong, also i do not know if the envelopes on the phatty are produced digitally, or through the use of analog circuits.
Honestly it’s gonna be pretty unnoticeable, I’m sure they use good resolution DACs on both for MIDI. Voyager is 14 bit, no? I’m not positive on the envs, but i think they are analog except the control knob for them isn’t RAC on the Stage IIs, although I recall someone saying the LP Tributes are RAC. It’s been a while since I focused on specs for it, it’s such a beautiful machine, there’s very little to be desired if you get the mod. Get both! 
Little Phatty envelopes are analog. MP-201 envelopes are digitally-generated.
Resolution on the MP-201 envelopes is 12 bits, ~4 kHz. Not bad for slower-than-audio-rate signals… they look very good on a scope. Analog resolution, of course, is nearly-infinite…
so, resolution: advantage LP
variety: advantage MP-201 (EG Hold, Looping, Lin/Log/Expo shapes)
The LFOs are currently very similar on the LP and the MP-201. Almost identical, in fact.