Well, I used to race a TC4 on foams, and now I currently have TB-03. I think the TB-03 is much more durable, though it may be that its just my driving that has gotten better over the years.
Right now, I have been having a hard time with dialing in my TB-03, but I've given myself some handicaps (must be totally TCS legal, including tires). The one thing I've noticed is that my TC4 would lean a little towards understeer, but my TB-03 has got inherent oversteer characteristics. Frankly, the TC4 was a great disappointment compared with my TC3. The TB-03 definitely can cook around the track much quicker, and gets through the corners a lot faster.
The TB-03 is a much newer car, and has much more support, so I would go with it. TC4 parts are becoming harder to find in stock.