We have just bought a 2010 16.49-1 OB. We looked at lots. The big thing we found was sun and water damage.
Sun fading the plastics and dulling the aluminium.
Water getting inside and swelling stuff.
A tip that we were given is to contact the seller and have a chat and get their address telling them you will drop around next week.
Then ring them when you are 20min away a few days later saying you were in the area. That way when they open it up you will get hit with the damp smell straight away because it has been locked up.
We found the hard cover models easier to open up and seemed to make more sense, being covered when open. On one of the outback van models you could hardly reach the top swivel locks or push in the canvas. On the hard covers this was not an issue.
Have fun. Really impressed with our new one.