ORIGINAL: caspar21
the 18ss kit has slightly less top end, same acceleration.
the g3.0 comes with a radio while the 18ss has some chassis hop-ups instead: re-enforced diff's, some other small stuff.
18ss comes with a clear body while the g3.0 is painted (i think).
if you need a radio or are completely new to rc nitro) then the g3.0 is the way to go as it is assembled and ready to go.
if you have a radio allready and are not afraid of turning a box of parts into a nitro car then the 18ss+ is the way to go.
sounds like the kit would be the better choice. I have a redcat volcano which is basically a copy of the mt2 and I've taken that thing apart loads of times