You have to hand it to Quark though. The only things I don't like about them is the fact that some have problems on 6S and the fact that they can't be programmed via computer.
...And the lack of reverse braking. Although, as CHC (I think) pointed out in some other post, there IS reverse braking if you have drag brake available - just not as nicely controlled as forward braking.
Even with the relatively few negatives, I still wouldn't trade the Quark for anything that I've seen out there right now.