I like that white percussion controller.
If you are oversees and getting the mod done is not practical (without great expense and risk during shipping), you ought to go for the CP-251 and get your hands on a decent Midi-CV instead like the Kenton Solo.
I was among the first in line to get my Tribute mod’ed for CV-out and while I’m not saying I am disappointed (because I have enough gear to do just about everything I can think of), the mod falls short in a few ways (see below). Having said this, I’ve read of folks getting things done in a special/unique ‘by request’ way so maybe there are other ways to have things wired up.
But when I had mine done:
Filt envelope (works just fine, no issues)
Vol envelope (same as above)
Pitch CV
Gate out
Mod bus
My complaint is that the portamento and pitch bend wheel do NOT make their way to the CV jack. This has been mentioned many times before and to me this is the single biggest issue. And while there are certain applications for having the external sound source ‘drone’, ideally, that 3rd OSC or whatever you connect it to is most useful if it bends in the same way that the Phatty does, and that means obeying the pitch bend up/down.
The Gate out, especially with the new duty cycle/pulse width is super useful, especially with the arpeggiator. You can use it to drive/step the murf, kick a drum trigger, advance an external analog sequencer, etc.
(but bother of these functions can be had with Kenton and you’ll get yet another Midi-sync’ed LFO)
Speaking of LFO, the mod bus works well enough but I’ve read that some folks have requested that the pre-wheel mod is what gets sent (vs. the amount of wheel). Again, Kenton and other midi-CV converters will let you bind a Midi CC to a control voltage. One thing that the Phatty has over the converters is that their midi spec is usually a 7-bit 0..127 value so it’s a bit coarse, vs the smooth voltage of the Phatty’. So check into this before making a decision.
And then there are envelopes. Useful in many ways but nothing that cannot be modeled with other gear. Multipedal is super useful for this, or you can cobble together a travel case with a few modules such as the Synth.com Env generator. It requires an analog Gate to trigger it so I suppose it’s not a turn-key solution (you’ll need Kenton also).
As always, mileage varies based on requirements. I like the CV-out, but CP is very good in many other ways. If I were only carrying two pieces of Moog gear (in addition to whatever else you have), it would be the Phatty (a given?) and a Multipedal if you can find one. It’s an absolutely incredible product but somehow the general public missed the point.
+1 to what was said above
The are 2 main uses for the CV out mod. 1) Use the phatty as a controller for another analog synth or 2) as a mod source or Both
If 1) postmod wheel mod bus and pitchbend and port is a must
If 2) premod wheel mod bus and port still a must but you you might not want pitchbend in the mix
Thanks guys, great advice.
I’ve just bought a CP-251 as I had the oportunity. I’m looking for a MP-201 as I let the oportunity go lately; I may have found some of them her and there…
Now, about the CV-out mod, being overseas is not a problem since I live like 20 miles away from my country Moog official dealer/tech. So I can drive my Phatty there, and drive to get it back. Plus I should have it fixed since the value push button is down.
When I asked the tech guy for the pre-modwheel mod, he told me he would not bother with something that is not properly covered by the warranty. So I guess the question has its answer for my own case.
About the pitch CV out, that is indeed a pity that neither pitch bend nor glide is transmitted. However I should be able to have some fun anyway as it does not reduce the possibilities to zero 
The Kenton or modular solution is not for me. For now, at least. I do prefer simple, compact set-ups. Heading towards the MP and CV-out… I guess 