I have 2 spools in my E-Maxx and i tell you what, it does not turn on power, you have to brake and get it to slide out.
I love the 2 spools though, it can take on anything, just make shure your driveline is bullet proof becouse it creates alot of stress on the internals and outdrives.
A happy medium is to only lock the rear, the only thing i dident like with this is that the front wheels dont climb they just spin while the rears create huge craters in the ground
Not thats a bad thing though, happy experimenting