About to purchase question ?

Hello Everyone
New to the board and will be new to Diesel trucks soon.
I've definitely decided to buy Ford for various reasons and my plan is to buy a 2011 at the end of the year either new or used with low miles. But I've also been looking at the used market from 05 on up and been seeing some good deals with options and upgrades that I would probably not purchase if buying new. As I've been trolling the various used sites I've been noticing a BUT load of 08's in the used market. Is there something about the 08's that I should steer clear of or is it just a coincidence. I am leaning toward the 2011 obviously because of new technology updated engine, transmission, frame etc. but there are some sweet deals on some of the older models that my bank account and wife would enjoy more. Any thoughts/concerns on my plan would be greatly appreciated.
Duc848