[Gustav]

That mount i was talking about definately provides a lot of protection against big shocks too,the whole assembly is very springy,the bushes are squishy and not done up tight and you can flex the whole thing considerably with one finger.The posts are plastic and flexy and the whole thing can spring about in a tumble,it takes the edge off the blows.It seems to have proved reliable in the truck,in real life.A casio G-Shock floats in a rubber bush i believe,similar principle.

Anyways..the 6061 vs 7075 thing,i've always looked at it like this,(disclaimer,it's just a theory from my little brain);it's possible to make a 6061 part equally strong as the 7075 part at very similar weight,it simply takes more volume of material.7075 is a similar percentage stronger as it is heavier to 6061.So using 7075 is not strictly necessary to get a part that's of similar strength and weight unless you're restricted to paticular dimensions or specifically need the surface hardness,such as in a diff cup where 7075 is required.7075-T6 still seems to bend long before it snaps in RC car chassis,so i'm not sure i'd be worry too much about metal fatique,it doesn't look like it'll be flexing a whole lot.i'd just descide based on strength:weight,cost,availability,machinabilty.