I got the racks and set them up immediately on my truck. The tightening mechanism to lock them to your racks is so easy and straightforward. Honestly the hardest part of the entire process was getting it centered on the racks (which isn't even Thule's fault).
There's no noise or downside to transporting boards up on the roof. I haven't really noticed a gas mileage hit yet, and it keeps wet boards outside the car when I'm coming back. Plus I'm not scared to leave the board on the roof if I leave the car for a little bit to grab food or shop. The racks are secured to the roof, and the board is secured to the rack. Pretty much the only thing that could get stolen is the bindings (for a snowboard), and it would still take work.
The one downside is with the locking cores themselves. When they work, they're great, but when your hands are cold because it's 0*F outside, it can be a little frustrating to get the key in to lock / unlock the device.