In 2008 or early 09 I bought Cobalts right when I could get my hands on them. I have used them on rigid frame geared, or single speed, I have used them to race XC and Epic 100 milers, 12 hours races, daily training etc etc. I have had to true them for actual issues twice, those were totally my fault. I have never broken a spoke, I have used with 4 different manufacturers of tires tubeless, and also ridden with tubes, with road tires as well.
I just got another bike and one of the conditions of the purchase is that they come with Cobalts again....need I say more!!! And they came 15mm I am so happy....
Stiff, responsive, light. Remember in that price are some really snazzy skewers, a very low maintenance hub (just remember after servicing hub to slide the rubber seal back into the rear hub) and a beautiful design.
have fun on your new wheels.