I have been running a TC3 since they came out and have owned many other cars since (Xray, XXX-S, Schumacher, Tamiya, Yokomo) and always go back to the TC3. If I were to say that one car is difinately more durable than the rest I would say Schumacher. They are almost bullit proof in my opinion.
If you brake anything more than the the front A-arms, front hub carriers, front castor blocks and bend the front hinge pins on a TC3 then you should really slow down until you get better or take up a new hobby. Sure, once in a while you will break any part on any car. The only real problem with durability on the TC3 are bent hinge pins. They are a thinner diameter that what most cars use.
While the front castor blocks and hub carriers are another weak spot, you really shouldn't be breaking them often. To be honest I would switch to the Losi XXX-S front castor blocks and hub carriers. They are a direct replacement with no modifactions other than making the steering turn buckles a little longer and they cost much less than the Associated units. The Losi front end is a little stronger and will give your car more steering.
Another issue I hear a lot about but have never personally experienced is the chassis tweaking because of the heat of the motor and the motor clamp. With the motor clamped down after a run, the heat can cause the chassis to tweak. I say I have never experienced this problem because after every run on the car, the first thing I do is loosen the motor clamp and place the car on a stand with a built in fan. This will eliminate any chassis tweak do to the heat of the motor.
Hope this helps!
Joe