I use Thule Racks with a 4 board carrier. The system is just as slick as the Yakima one. The lock down system for the racks to the vehicle is slick and reliable.
As far as Yaks go. They have been a reliable company for years, but don't buy used Yakima's. They had a couple of season where the rack would blow apart on your vehicle. Even if everything was secure. They were excellent about replacing the racks and any gear that was damaged as a result. It is still something better avoided. Imagine your snowboard going through someone's windshield to get an idea of what I am talking about. They have since fixed the problem on their new racks from what I understand. So you should have no worries there.
Overall, I do like the Thule system better, that is why I went with it. Their really isn't much of a price difference between the two systems.