i just installed my lift a couple a weeks back and the ride stayed the same my MPG did even drop with just the lift some claim it will due to more drag. i had my 35's put on sunday and that made a difference with the ride, the truck rides better with those then the 33's due to more tire wall. i haven't checked my mpgs yet because i have only put about 60 miles on it with the tires.
Had mine for going on two years now with 35" Pro Comps. Mileage averages around 12.5 to 14.0, depending on a few variables. I have had no problems with the lift itself, or ride quality.
*However.....if I had it to do again, I would go with a suspension lift to achieve the clearance and larger tire size to do the mild off roading I do, simply because of the added stress the larger diameter tires impose on the 'just adequate' stock front suspension components. I have had to replace both front axles, and am experiencing some significant ball joint/ control arm wear and tear due to running the bigger rubber. My truck has 127,000 miles on it now, and I have had the body lift for about 30,000 of that. Remember that bigger tires means bigger rotating mass, which means more to keep in balance, and more vibration when they aren't balanced (due to normal wear down). Not to discourage you at all.
Just depends on what you need, want , and plan on doing with your lifted truck...hope this helped. Good luck.