if the tyres on the 4wd losi are the same as the ones on the 2wd then I think they will be ok. probably not as much overall grip as course kings, but will probably provide a better ballance. Personally I'd rather have a well ballance car that was nice to drive, rather than having to fight one that has got too much grip and wants tip over all the time.
On a more serious note (for us), the pull start on our generator has broken. Will we be able to bump some power off someones genny? We will provide fuel as there are 2 of us.?