Speedydave- My pit partner runs a MTX3 and it is a good car, but I really like the NTC3 either car will break if you are hitting walls or other cars so you must learn to drive clean, this will also help with lap times more than anything else.
If you have good access to parts I say go for the NTC3. If money is a concern get a used team car and put on the new V2 suspension and you are ready to go.
A good set up and clean driving will get you ahead of 70% to 80% of the guys at any track with any good out of the box kit. The used car I bought had been raced for two years buy a guy at our track and he had never done better than mid pack in the B-main. I took his used car and motor rebuilt every part and put a good set up on it and put it in the middle of the A-main, he was in the C-main with his new MTX3 and Turbo 3 port motor.
Speed is about clean/smooth/consistent driving with a good setup.