Guys-great questions. I've studied this for months now. There are a couple forum members here that have their trucks and have upgraded to the LT275/65 20 tire. I am considering the same.
You might find this helpful:
(this link is what justifies the switch in my mind).
One thing I've learned, however, is the tire will be much heavier, which may decrease your mileage. I suspect the LT tire will ride a bit "rougher" than OEM tires, but with air suspension, this does not concern me.
Hope this helps...keep us updated, and I'll do the same.