The 1515 should let you get a bit more top end and keep reasonable temps.
I wouldnt try overvolting the MMM. Castle has stated in no uncertain terms that the MMM WILL NOT handle voltage over 6s lipo. Period. So if you try it... It will likely be at your own risk.
I can't decide if its more fun
to make it...
or break it...
Yeah, I suppose... going from 3s on the mm to 4s is one thing, but 6s to 7s is another thing, much more risky. Seeing as it's already hard enough to get a controller working safely on 6s for cars.
“The modern astrophysical concept that ascribes the sun’s energy to thermonuclear reactions deep in the solar interior is contradicted by nearly every observable aspect of the sun.” —Ralph E. Juergens