First I tried Roccat Powergrid, but that had a fixed grid. I couldn't line it up with the tablets behind the Cougar MFDs. I still use Roccat on the 2 side displays, for its default system and sound panel. Development of Roccat is now halted, you can't publish any custom Power Grids anymore.
Then I switched to LEA extended input. LEA is fully customizable, it even uses VJoy,. The only catch of LEA is that it is tablet-develop-oriented. You could design your screens on a tablet... with PC you emulate a tablet. That causes a lot mouse action, very precise positioning is harder. The Shield and Power screen are tons of layers above each other and mimic animation. A lot of work, but I published my screens at LEA extended input.
Game Glass are fixed screens and you must pay if you want to use multiple tablets. My tablets aren't that old, but they aren't supported... 3 Samsung Galaxy and 2 Asus tablets... Not exactly exotic tablets, but still not supported. 3 good reason why not to use Game Glass. The animations however are more advanced, but I probably can't get them good aligned behind the MFDs.