I only have experience with the Thule XT Pro2 with 2" hitch that I bought off here from someone for a great deal, and I have only used it with 2 bikes so far, a few times with 2 MTB (26 and 29) and a few times with 2 road bikes.
When I was looking into a rack I had the same problem, totally overwhelmed and they are so much money brand new. I decided on this one and I waited patiently to get the one I have used for a decent price, but I guess you could try to catch a sale at some point.
Pros:
- as others have stated its built solid and the trays accept all kinds of bikes out of the box including fatbikes.
- no frame clamping its all from the wheels
- setup and operating it are not that complicated
- key locks the hitch to the car, and also the built in cable locks that come out of the clamping arm
- solid build and the bikes dont seem to move around a lot with any bad bouncing
Cons:
- the main 2 bike part is a bit heavy, but not terrible though I didnt really compare it to any others in person. I could see with the add on this thing will be a beast size wise.
- cable locks are not foolproof but I am sure no one on here would rely only on those and leave the bikes on the rack for any extended period
- With 2 MTB bikes I had some minor ground clearance issues on my 2013 Santa Fe when backing up into my driveway, but I have an aftermarket Curt hitch on there, and I probably went a little too fast and scraped it a little. Good thing they designed a little steel skid plate on the hitch just for that purpose so no damage.
Overall I would probably buy this one again if I had my choice, mostly because I got great customer service. the rack I got was missing one of the rubber guards from the rear wheel strap on one of the trays, and when I emailed Thule they sent it to me free with no questions asked!
Hope that helps and good luck.