Sorry to hear about all your problems. I have the Vortex EXP pro (similar/same chassis) and have only had one issue: the stock ESC is "clunky". It seemed like a radio issue or voltage cutoff issue but wasn't. I replaced the bulky ESC with a Hobbywing EZrun 60A unit and all is good. The truck is very controllable and smooth. Also with the Hobbywing, the ESC can be tuned for all parameters.
As for the drivetrain, I have only changed the spur gear once. All the dogbones are solid. Maybe you got an earlier production unit? I am only saying that my Vortex seemed to have the bugs worked out of it. For sub $200 retail RTR it was a good buy and actually pretty durable. I may have got a bad ESC, but I half expected it for the price. The motor itself seems strong and top speed with a good 7.2v Nimh is high....high enough I haven't even switched to a lipo.
Mike-