Well, to be honest, 6s Lipo in a Crawler

80 Amp continuous

...maybe I'm missing something....
I've two Crawler, a 2.2 and a Big Scale (look at my signature) and never go beyond 3s lipo. My motors are brushed, 540 size for the 2.2 and 600/650 for the big one. Maybe in a stall situation they reach 30 ampere, but normally they don't use more than 10 ampere.
On the other side, the ESC has a quite standard BEC rated a 5a, that is not enough to drive the servos usually mounted on a Crawler, so You need an external BEC anyway.
Yes, the price is actractive, but for the same bucks You can get a Castle Sidewinder, that can also drive brushless motors and is perfectly rated for a crawler.
Bye, Andrea.