It works fine. In 2788, the way MPGs are handled internally is different. Now there is the concept of encoders that plugins can "export". And there is a new tab on the Mach config labeled "MPG" of all things.

In that tab, the user can associate a Mach MPG (12 to choose from) to an encoder from any device. %max vel and %max accel are there as well as reversing the direction.
For many of you, if you had script based setup of the MPGs, then that stuff will need to go away.
The shuttle plugin exports 1 encoder. The center wheel. Additional button functions were added to allow the MPG axis selection as well. One thing to note is that MPGs are separate than regular jogs. The MPG axis can be selected independently of the jog axis. Currently, there is not a way to select both the MPG axis AND the jog axis with one button function. Not sure how to handle that at the moment.
My setup is as follows:
MPG#1 -> /Shuttle0/InnerWheelCount, 1 count per detent, accel% 25, velocity% 35, reversed.
The first 4 buttons in the top row of the shuttle pro are:
1. MPG1 Select X
2. MPG1 Select Y
3. MPG1 Select Z
4. MPG1 Select A
The MPG increment is the current jog increment by default.
So all I do is press one of my 4 buttons to select the desired axis and start dialing away on the wheel. And it works really well. I wish the detents were a little more noticeable on the shuttle, but it is what it is...
MPG#0 is configured to another MPG, so that is why I used MPG#1 for the shuttle.
Steve