RE: Team Associated RC18B Pro Kit or Duratrax Vendetta?
Unless you are drag racing someone on the street, the 3S lipo is WAAAYYY too much for dirt. 2S will be plenty. The Spektrum is a great choice, the ESC and motor I don't know. I personally have the Mamba system in my Mini-T, and the Quark 33/Permax in my Vendetta buggy. I've had nothing but great experiences with the 180 can Mamba motor.
Good luck!