I bought my 7yo a HCG roller and quickly picked up many parts I knew would likely need replacing quickly. I did a few preventative mods as well like a roll cage and RPM undercarriage servo guard. With the roll cage, I've not had to replace a body in two years. My son has two and they are both in great condition.
The only thing I've had to replace due to breakage was a front LCA. But, I had already bought the rpm upgrades so I quickly swapped the fronts out. He is still running the plastic axles even though I picked up a set of solid state drives. He's not racing and they are like new....so why fix if it isn't broken?
I did go ahead and upgrad his hex's to aluminum as they did show signs of wear. I also replaced the shocks with the GTR versions because I was tired of the caps coming off.
I also installed an old TheToyz chassis zipper shroud to keep out dust/debri and installed a swaybar kit.
So a few things I found helped with this truck. So the only real "repair" I've done is the LCA and maybe the hex's. But I'm sure the way my son loves to slam into curbs and mailboxes that I would have replaced much more by now without some of the preventative mods.
Slash 4x4 - HCG
Kraton - Basher (4s)
Raider Mega ('14) - strong chassis/weak electronics
Dromida Ominus - consistent and dependable.