I'm pleased you said that, as I have just ordered heaps of them with the GX II's .
We have been running the 2072 on the team driver motors here, and they are performing awesome, with pretty good run times.

At our local track which is known for hogging the gas due to it's fast flowing layout, we have got an extra 1.5 min run time over the GX-7R in the same buggy using the 2072 on both motors, so the GXII is starting to show it's true colours now it's fully bedded in.
I ran a 2013 pipe on the GXII for a bit. It was nice, with plenty of power right across the board, and it sounded real nasty too , but I don't think I was getting the same economy as the 2072. Will need to test further on that one.
For the time being the 2072 (seeing as it comes with the motors in the combo kits at a very reasonable price) looks like the pipe to run on the new GXII-5RHO's.