@2revo1maxx I'd say the must have's for the X-Maxx would be good LiPo batteries, RPM A-Arms (82352), and motor fans. I'm also not a big fan of most any RC manufactures bearings and recommend checking out FastEddyBearings as well.
One thing that helped me keep my XMAXX up and running was shimming the driveshaft pinion that turns the front diff assembly. The mesh was too loose stock and any sudden jolts would allow the gears to hammer together and shatter. Basically i found a thin washer that i could install on the shaft before the pinion, which tightened up the mesh a bit. This stopped the gear breaking problems i was having and alot of others were - this was a 6s Xmaxx without the helical gears. I would only bother if you have similar issues, but it worked wonders for me - I had a diff gear that was already starting to loose teeth when i did the mod, had a new part ordered, and that part was never used the entire time I had the truck since the shim worked so well, even with a gear partially on the way out.