Luke:
As it is KEH this is probably not an issue, but you should confirm that the grip is accompanied by the proper connector for the Pro. The connector is the thing that permits use of the trigger release on the grip, and the connectors are different between the Super and the Pro (they are a slightly different shape, and therefore don't fit on the camera they are not designed for).
I actually bought my Pro, because the connector I bought for my Super was the wrong one
.
The good thing about all this is that the connector also doubles as a cable release adapter, so you won't need to buy one of those if you get the right connector with the grip.
Have fun - they are great cameras!
Matt