Foo - Universal Cartop Carriers for kayaks?

Anyone know anything about them? Good? Bad? Will the kayak slip off the roof? Here's a link (http://www.llbean.com/webapp/wcs/stores/servlet/CategoryDisplay?page=universal-cartop-carrier&categoryId=36508&storeId=1&catalogId=1&langId=-1&parentCategory=4701&cat4=5599&shop_method=pp&feat=4701-tn) to what I'm talking about...

I really want a kayak, but the cost of a roof rack for my car would be just as much as the kayak itself. I'm looking at a decent kayak on craigslist (Old Town Dirigo 120 (http://www.oldtowncanoe.com/kayaks/recreation/dirigo_120.html)) and it comes with a paddle and the foam cartop carriers. This would definitely simplify things for me if I didn't need to get a full blown yakima rack system.

I drive a sedan with a sunroof (will the sunroof get in the way?)

Thanks in advance for any input.

http://cdn.llbean.com/products/sporting_gear_apparel/36508/images/L36508_Gray.jpg

I'd probably get a better set of ratchet tie-downs that what is shown above. ^

Would tightening them too much potentially damage the boat?

Used a Thule kayak rack with just the included blue nylon clincher straps for my windsurf boards for years.The kayak holder looks like a big U.
Most bike dealers sell either Yakima or Thule.

I'd probably get a better set of ratchet tie-downs that what is shown above. ^

Would tightening them too much potentially damage the boat?

I think you would be fine. If you don't use a rack, I would recommend bow and stern lines. These should be taut, but not overly so. I think ratchet tie-downs are overkill for this application.

Good? Bad? Indifferent? I have a Greenland II Folbot. I can pack it into 2 bags, put them in the trunk and leave the roof rack for bikes. Consider that option.