4x4 SCT and rally cars are very popular ATM... They are the same physical size as a 1/8 buggy but are considerably lighter... They do have some preformance dissadvantages compared to a 1/8 buggy. But they are a lot cheaper to maintain.... Especially when looking at the electronics. Durability wise the 1/8 buggy wins, but that goes with out saying how durable 1/10 SCT's are.... Generally they are just as strong as there truggy counterpart but with the addition of full fender body, front, side and rear nurf bars.

or there is another option.....
I'm assuming ur son has a Traxxas rustler??? With a few little goodies u can make those things nearly indestructible.... And it can be converted into a very durable SCT with a very low COG
got any pics of the rustler?? It can help me identify what exact model it is.... What colour is its ESC?