I haven't seen the Mont Blanc attached so can't comment there or the Thule. The Yakima EZ-Rider clamps to the factory roof rails on the wagon, only on the sedans do the Q-towers clamp to the car's sheetmetal.
With any roof racks, make sure you follow the directions carefully. Not following the directions to the letter can cause damage to your car. I know most cars will give a rating for the load the roof can take, I don't recall offhand with the Scooby. If you exceed those loads, bad things can happen.
A properly mounted roof rack can take quite a bit of stress including exceeding the factory recommended loads. My Yakima rack with Q-towers on my old Camry had 3 bikes on the roof doing over 100 mph. I've also been on my roof rack with the car moving also.
If you do stupid things like driving your car into the garage with bikes on top, you will appreciate round cross bars over square ones. You will still end up with a destroyed bike and a bent bike tray, but the round cross bars allow the tray to rotate which lessen the damage to your car.