Pros: Very secure mounting.
Can be expanded to hold 4 bikes (2" receiver model)
Doesn't touch the bike's paint.
Accepts 26" or 29" wheeled bikes.

Cons: EXPENSIVE!

Recommendation: Two of my friend have this rack on their SUV's. We can load 4 bikes in minutes and they do not move. Period. (tested from Colorado -> Moab and Denver -> Monarch Crest)

The fact that nothing touches the bike frame is neat, and we have a mix of 26'ers and 29'ers and a quick slide of the wheel trays handles them all.

If I didn't already have my roof racks, this would be my choice.

Pros: I love the fact that you don't need to lift the bike up to far. The no touch on the frame way of grabbing wheels only. Fold away, and locks included.

Cons: None!

Recommendation: This is probably one of the best systems I have come across. Specially if you have a heavier bike this is what you need, this unit is solid. Holds the bikes secure with no chance of the bikes shifting around. All you need is a class 1 or 2 reciever in either 1 1/4 or 2" just make sure you get the right one.
Perfect for those who have a tendency of forgetting that they have a rack up top when driving into a garage.