I had the same concerns you do. But after reading up on the thread for the D8 I was convinced that the few bad things about the buggy were not any reason for me to not get it.
There are some cvd issues, but if you take care of them (pack them with grease and cover them) they will hold up. THey do also make some upgrades in that area. I haven't tried them, I am going to stick with the stockers for now.
As for durability, I think the Losi and Mugen are probably a little more durable. But the D8's parts are much more affordable, so it's not a big cost to keep some spares on hand.
IMO, the D8 is pretty much race ready out of the box. I know several good drivers that are running them mostly stock. HB makes a ton of lightweight parts for the D8.
Hope this helps.