I have a TT-01 that is awesome for bashing. I tried to race it and...well...it is awesome for bashing!
I was curious about the 4-tec as well for another basher and was told that they are crap. I also have a TC3 and an Xray FK04 that are better suited for racing.
Personally, if you are looking for something that is not for racing, I would go with the TT-01. They are durable, the parts are easy to find and the bodies that Tamiya makes for them are very scale looking.