They are too few to really be known right now. Of the few of us who own ZD cars, few have the truggy, and even fewer have broken anything that cannot be replaced locally. At least, nothing that I'm aware of. I've cartwheeled my buggy a few times with no issues, and hit a tree at relatively low speed. Not really a good durability test.
If parts support is something that you are truly worried about, ZD Racing may not be the brand for you. At least for now. With ay luck, they will become more mainstream. With the RTR kit as good as it is, they could give a lot of companies trouble.
Losi 8ight-TE 2.0, OFNA Hyper Sprint E-conversion, Losi e-LST XXL, Losi 8ight-E 2.0, Team Durango DESC210, Quanum Vandal