Hi Josh,
I have the rally car, mine came with the schlesser body, but its the same apart from that. The stock motor isnt bad, it starts and runs and holds a tune pretty well - its the same motor in the MT btw. Only issues I have had are broken cvds and dogbones, but thats mainly down to me fitting an OS18 CVR-X, which makes it pretty quick - 60mph ish, with the tallest gears that cen sell. The stock motor is strong enough to strip out the plastic wheel hexes, if thats anything to go by, not a regular problem, but I always kept spares handy.
I dont think you would actually need to gear it down so long as you get a 2 speed version, I tried the MT pinions in it and it simply made it slower. Same goes for the diffs, personally I would leave them as they are. Obviously it will eat plastic spur gears if you dont mesh the gears right and check and threadlock screws etc. Spare spur gears are recommended anyway tho - stones etc will still destroy them.
Overall its strong enough for what its designed for, so long as its properly maintained like any nitro. Big jumps will bend the chassis tho, anything much over a foot - 18 inches high at speed will probably hurt it, if done repeatedly. The plastic plug that works the brakes will melt if used a lot, so the metal plug and metal brake disc are a worthwhile upgrade. On the plus side - it is pretty fast, Ive upset a few touring car boys with the outright speed, and with limited travel shocks and stiff springs it handles pretty well on tarmac too.
On gravel and dusty areas, its loads of fun and in its element - so much so its easy to hammer it a bit too hard! Softer springs than stock and lighter shock fluid etc, will give you loads of fun on this kind of surface. And of course all the FunFactor hopups will fit it.
Bit long that... sorry!
Heres mine in its glory days...
Oh yea, check my little website in my signature below for mods and pics etc