i have a revo... it's just a more technically advanced machine. think about it... it's something like the evolution or... REVOlution of monster trucks.
the horizontal shocks work like a dream, and they allow the truck to handle like no other. i mean... they're modeled after formula-1 racing cars!! since they're in the body, they stay away from a lot of debris that damages conventional shocks. for very consistent handling, spend the $20 and get the ti-nitride shafts. good upgrade.
the chassis is incredibly rigid. more rigid than other, i would say. this is because it has shape. it is bent all over the place, but those bends keep unnatural bends from happening. deflection is based on the inverse of the height, cubed. this means that the higher, or taller the chassis is, the less likely it is to bend (by an order of 3!!). if you want to bullet proof this area, go with the hardcore full skid plate.
almost all owners end up going with a single steering servo setup. you'll want to find a servo with at least... meh, 200 oz/in of torque. some say 150, but you're better safe than sorry, especially if you put 40 series on it.
RPM arms and axle carriers aren't necessary, but they're awfully nice to have. that added sense of security has its advantages when bashing, lol. honestly though, any R/C vehicle i will ever own will have every available RPM part on it... they just make nice stuff!
oh... and get rid of the EZ-start right away. get yourself the pullstart and a glow starter, and you will be a very happy camper... trust me. those one-way bearings are expensive!
there you have it. those are my recommended mods to keep yourself busy for a while. don't get me wrong, a stock setup will do you just fine. but... if you're going to do something... do it right! right!?