Check out the Giant scale forum for all your questions regarding 1/5 scale RC cars and trucks.

Personally I can tell you that once you go large scale you'll never go back, the physics, the sounds, the handling, it's all magnitudes more realistic and thrilling. To me it's where the soul of the hobby is. If you can afford it, it's the best side of the R/C hobby to be involved with.

In any case, head on over to the giant scale forum and browse around, you'll get to know the options better that way.