I had a TC3 several years ago and thought it was a great car. It had its quirks, but it was a fun car to work on and do all the mods (moving the cells in, rolling the sides of the chassis, etc). When the TC4 first came out, I bought one and was sorely dissapoined. The parts quality on the TC3 had never been exceptional, but the TC4 seemed to be a step in the wrong direction.
Within a month or two I sold the car and bought an Xray T1 FK. The different was very noticeable. Not only was the car easier to assmeble, the added precision of the parts was easily seen on the track. The car responded much better to adjustments.
AE seems to have caught on, and the TC4 FT looks to be a step in the right direction.
Josh