Ext. chassis 4 emaxx...???

Right now I'm running a Feigao 9XL, and MM/BEC disabled for the Hobbywing UBEC. On the first two runs the temps never got above 120 for the motor and 110 for the MM. It was 8 in the morning 72 degrees outside. I'm also lucky that I have a couple of the older MM's from my crawling days. They can go to 5S with the BEC disabled. That was with the stock chassis and Proline Maxx Mashers. I had it geared 18/66.

I changed it to a 22/66 now but I haven't run it yet. It'll probably overheat due to the Big Joes now. So I might have to go back down to an 18T.

Is the Neu 1515 1y/F really that more efficient? And I can't use Neu's with MM's, right?

If it is I'll be ordering one sometime next week for sure.