Hey Vmax.. always good to see another MG owner!
On the batt's, I use high capacity AA NiMh's in my unit. I've got both 1850's and 2100's and it does make a huge difference coming from Alkalines. I went with the rechargeable AA's with the higher mAh rating for longer run times.
You should note though, there are a couple of caveats to beware of with the AA NiMh's:
1) Make sure the batt's don't have the solid cap on the positive side, they should only have the metal tip like a normal battery. The problem with the full metal cap ones, is that they short out the 'multi-polarity' battery system the MG uses in the carriage and the controller.
2) You might want to check the size of the batt's first. Steve was sayin' that his NiMh's were too large to close the lid on his transmitter. I've noticed that mine are definitely larger than Alkalines and make for a snug fit, but still work alright.
Other than those two things, once you have the right batt, they work great.
Won't have as much jam as the Hex though, as it's only 7.2v with 6 AA NiMh's. But it depends what works for you.. I like the longer run times.
Edit: I use steel RS4 pinions.. have a 9T and 11T.
Hope this helps man..