I have the Thule Universal Pull Tops and I can tell you now that I would've rather purchased the Yakima Fat Cats. The Pull Tops are not worth their price -- for some reason, the plastic housing at the ends covers more than it should, eating up a few inches of ski/snowboard space. This might not seem like a lot, but it actually makes the rack just a little too short to fit all that it claims. I actually had to used wire cutters to get rid of some of the plastic material covering the ends (if you bought it, you'll see what I mean). If you have snowboards with tall bindings, the pull top feature is useless, I think even with the Thule load bars, as your bindings won't clear the bars running the length of the car.
I also think the Pull Tops aren't very attractive -- they sit kinda tall and make me lose about 1.5-2 MPG. That may or may not break it for you, if you're set on a rack, it probably won't. My friend has the FatCats on his Land Cruiser and I really like how low profile they are in addition to the fact that you can use almost all of the rack length. Plus, the Fat Cat uses a ratcheting system which allows the racks to lock "taller" in case you're baselayers are thick (problem for me with the Volkl AC50's. The Pull-Tops use a locking mechanism.
If you're set on the Pull Tops and you have tall bindings that cannot be offset enough by the Thule load bars, I'd grab the factory racks. Well, hmm... maybe not. If you have tall bindings, you want to have some clearance so that the bindings aren't up against the paint on the top of your car. If you're a skier, the factory rack + Pull Top has enough clearance so that the bindings don't touch the paint, but not enough clearance so that they can clear the factory rails running the length of the car. Most ski racks you buy can be mounted on factory cross-bars -- the Pull Tops and the Fat Cats can for sure.
Hope I've been helpful. Go with the Fat Cats! You won't be sorry!