I bought this rack on super sale. I would not have paid full price for it, but it is a decent rack.
I have a Volvo with thick aero factory bars and this rack just barely fit. I had to use the longer screws it came with (at least they came with it!) You don't need tools for installation, but it does take a bit of adjusting to get the fit snug. After you get them dialed it should be quicker to take them on and off in the future. The parts don't seem very robust. The plastic nuts are a little flimsy. Other racks are probably more solid.
The slide feature is kind of cool but it froze when i went from rain (Seattle) to snow (Steven's Pass). It is still easy to get the boards in and out tho. I was able to squeeze two boards side by side, but they were by no means wide boards. I measured the grip area at about 23" wide if you want to check your boards side by side. Never tried 4 but I wouldn't anticipate a problem. It was nice that the locks came with it. The other racks I saw didn't include the lock cores.
Overall, the rack will get the job done. I'm not particularly in love with it. If you can't get it during a sale I would go with one of the better racks.