As long as you drive indoor on carpet or VERY smooth tracks, the XXX4 is a good car.
Seriously : almost everyone in europe gave up on the XXX4. It seems to be designed for the american style smooth 'blue groove' tracks. As soon as you hit bumps, it utterly fails ! There's a reason Losi re-issued the 12 year old XX4.
I had a Kyosho Lazer ZX5 last year but decided to ditch it because of serious reliability issues I couldn't completely solve (leaking shocks, breaking gears, breaking front shock towers, ...). I recently bought a TRF501 and for now it has been brilliant !! Easy to setup and a real tank ! It can take more abuse then any other 4WD IMHO (indoor carpet races are very hard on offroad cars
) and just feels planted.