Without brand bashing..... some facts:
The 4tec is very old design with some designs resembling early generations of hpi's rs4 and rs4 pro cars. Thats very old. As well this car has never been marketed as a race car, its basically a low end sport car.
The TC3 remarkably is an old design but its a race proven design that has been winning at national and international levels of racing. For the non racer this mean a car that is supported everywhere and a car that will win races with the right driver.
Its not a matter of trust of one company over the other. Traxxas has probably the best after purchase customer service there is. But you should not need sercive for either car..
IF your looking RTR they both come RTR, Again the TC3 is simply a better performing race car. That will double as a back yard basher. ITs shaft drive will be better suited over the belts of the traxxas ifyour running in less the clean areas.
As well regular maint work on the TC3 is much easier then on any belted car.
If your thinking about racing.. Skip the traxxas completely.
Performance RTR? Losi XXXs or AE TC3. There the only 2 to look at for "RTR" performance.