I've got about a year on my E-Maxx, and that includes the first owner being really careless, and then the truck got hit by a car. So I've built it up pretty explosion-proof now.

Must Haves:
Traxxas Steel Center CVD's - TRA5151R
RPM A-Arms
Metal Front and Rear Skidplates (I prefer the Integy Titanium ones.)
Aluminum Rear Gearbox Housing
FLM Diff Cup w/ Modified Gear (For the Rear)
Aluminum Shock Caps if you have Traxxas Ultra Shocks
Aluminum Front Bulkhead (I use the Integy Forged 7075 Bulkhead)
RPM Rear Shock Tower
Robinson Racing Gen3 Spur/Slipper Unit and Hardened Steel Pinion (The TRX one always burned up for me on 5S).

Nice to Have:
RPM Bulkhead Braces
RPM Tru-Track Rear-End
RPM Front Knuckles
Traxxas Big-Bore Shocks w/ RCRaven Springs
RPM Front Shock Tower
RPM 3-Piece Skidplate Set (Saves your truck!)
Aluminum Steering Crank/Servo Saver Set

For what it's worth, I've got a year on my plastic wheelside driveshafts and have yet to break one or twist one, and that's on 5S with 19/65 gearing wearing Pro-Line Trencher-X's. The plastic driveshafts aren't to be underestimated, they'll put up with a thrashing. I beat the utter crap out of this truck and it keeps coming back for more.

The only hingepins you really need to worry about are the front end, and with the forged aluminum bulkhead and RPM arms, you usually shear them off rather then bend them, so it's easy to just replace the pin, though I haven't wrecked a pin in three or four months, and that's using the stock Traxxas pins. I never could justify the heavy-duty titanium/etc pins.