I have a ZT2. It's nearly unbreakable! Only disadvantage about the car is that it comes with brass bushings and has not any slipper clutch. But that's easy to fix, just change to ball bearings and you can also modify the Losi slipper to fit in ZT2/ZK2. There are also not any options for the car, except Thunder Tiger's own but they cost ££££ but who needs option car for a car that won't break?
In my opinion a ZT2/ZK2 is a good choice. I've a ZT2 with Mamba 6800. I haven't broke a single thing on the car since I bought it! (about a half year ago). The parts are pretty cheap if something will break though
I'll try to convert my ZT2 to a mini-B4 as soon as I've get enough cash to spend on it. Last helicopter crash wasn't so good for my wallet...