RE: hpi savage into rock crawler???
most people will say that nitros cant crawl, but if theres a will, theres a way i guess.
the reason being is that nitro engines dont have enough low end torque, so they end up going full throttle bawls to the wall over small rocks, rather than slowing ascending up high degree slopes like electric crawlers.
in my opinion, go for it. prove other people wrong, try new things, be willing to make cuts and by parts for planes, helis, etc (gear reduction units)
be a pioneer!