My RC10 goes everywhere around here. Grass, leaves, dirt, sand, mud, ditches, pavement, gravel roads, hillclimbs, even to the track. Get some nice tires on an RC10 and you'd have a blast!
And Çh®i§tiªñ is everybit right in my opinion. The RC10GT and the Losi XXXnt are the best. I personally LOVE the RC10. I get GREAT handling on ANY terrain, and excellent traction. I can't seem to get it stuck without it being on an insane hill or something of the such.
Today the track was really broken up with loose soil. Me and the losi that were there were doing great, I had the definete advantage in traction and handling.

Specially in the triples straight at the track. I was more of a "powder" than anything. I could ditch him evertime. I say it's the little more wieght I have, but even with the dumb motor I have, I still beat him out of the hole because of the traction. We were running very similar treads.

I'd say for sand and stuff, my personal opinion would say the RC10, for the pavement.. I'd go with a losi, since the traction difference from the wieght would be VERY minimal and the losi would probably be able to have an advantage with the power to wieght ratio.

I could fix that, but I'm a dirt burner
As for the buggies. Heck way they are. They are insane! They don't handle anything like a stadium truck. I like them, but they are TOO fast for the handling to me. I'm not putting them down or anything, but I'd stick with a stadium before I got a buggy.

That's me though. You may like that. Though, I wouldn't mind having an OFNA buggy to play around with
And monster trucks. YEAH!!! They are a ball to play with. Not much for the handling. I'd say they are more like.. an oversized truck that is tooo overpowered and has a very high center of gravity, but will go just about anywhere. Rocks... hills... Tree's, I've seen T-maxx's do them all
