[Patrick]

I knew what you meant by 7 cells, but Aangel is a single pack type of guy so needs a bit of help when talking e-maxx. :p
14 cell (good cells) e-maxxes are pretty quick, but mine still couldn't keep up with the 12 cell brushless maxx's at racing. Even when I put 20t pinions on (18t stock) I would still lose a few metres buy the end of the straight and hard accelerating out of corners wasn't even close. Also I think it kills the titans a fair bit quicker than 12 cells, but they are cheap to replace.

I don't think the Velineon (esc) would be very good in a maxx if your want it to be faster that a 14 cell e-maxx, since it can only do 3s lipo, and 4s or 12 cell nimh is usually the minimum most people here would run in a maxx sized vehicle.
The motor will be too small to push an e-maxx around quickly. It won't have enough torque so it will be struggling all the time, meaning more current draw and a lot of heat. Using low voltage and a small motor I think will probably make runtime worse if you gear it for the same speed as your titans on 14 cells. Sorry if that's not the answer you wanted to hear.
Maybe a MM and a 9xl on 14 cells would be good. With stock gearing it should be about the same speed as 14 cells on titans, but with better runtimes and more torque. You should be able to gear up a bit for more speed, but it could start to affect temps and runtime. Maybe even a 10xl if runtime is more important than speed.