I have been riding these wheels for a few hundred miles now and I can't believe the difference it made to my bike. I'd hear that Mercury made a great wheel and the price convinced me to pick a pair up. I immediately felt the stiffness upgrade over the average aluminum wheels I had while pedaling up hill and was convinced I had made the right choice within a mile. I found the change in performance on the dh was even more profound than the pedaling help. Suddenly I could hold fall away corners covered in gravel at speed, I was able to rip around tight turns with ease when before I had to think a little, and the berms were well, I won't ruin the feeling for ya.
I did have to mess with my suspension after the first ride, mainly the low speed compression and rebound fine tuning, but I did remove a token from the fork and a band from the shock to compensate for the added stiffness in the ride. This surprised me quite a bit, but the added stiffness in the wheels aids in precision on the trail that shows itself in line selection and cornering while the suspension being adjusted to maintain the plush feel I'd expect from a bike.
Arguably the most important part of any expensive wheel set is the durability. I know wheels get destroyed, its part of mountain biking, but I don't want to replace a wheel set every year or two. Last weekend I was riding in southern Utah (see pic) and detonated a bearing in my lower linkage so badly it seized the bolt in the linkage and required extreme extraction techniques to remove. The hit I took on the bike was by far hard enough to taco a wheel, and I was worried that I might have ruined my new wheel set. Upon inspection I found that not only were the wheels OK, but neither front nor back needed to be trued. I would highly suggest these wheels to anyone looking to get on carbon wheels, especially if you're looking to do it on the cheap.
Another awesome aspect of these is they lack the gaudy appearance of a lot of carbon wheels, they still have a little flash to them, but they're simple and clean.