OK, I know this is an old thread - but I think this may be of use.
Having read the previous posts I bought an X-Rack 'Stealth SQ' from the given link.
I opted for the Stealth SQ as it spreads the weight of the load - remember that the rack sits directly on the roof of the car. It fits perfectly and in my opinion is well worth the money.
A couple of tips/observations:
The load must be at least as long as the supports, otherwise you may as well strap it directly onto your roof. For shorter loads I use an old mesh dog guard to support whatever I'm carrying.
Make sure your roof is spotlessly clean, otherwise you run the risk of scratching the paintwork.
Practice putting it on - be prepared for some strap vibration until you get it just right. You may be able to live with an annoying buzzing noise for short journeys, but over a long period of time it really starts to p*** you off. Putting a twist in the front straps and tucking all the excess away is a good way of reducing the noise.
I have just completed a trip from Salisbury to Manchester and back (about 400 miles) and it stayed secure all the way (the dog was in the boot and my kids were in the back).
Overall it is an excellent bit of kit, good value for money and very useful if, like me, you have kids and a dog that you occasionally need to ferry around with all the associated ancillaries.
(I don't work for X-Rack and don't sell them or make any profit from the sale of their products.)
Hope this is of some help.