I did it last week....
I have some limited experience here. I just had the axles flipped on my Jayco AFTER I moved the leafs down two holes (I went from a '99 1500 4X to my '03 2500 4X). Now the trailer sits WAAAAY up there - unfortunatley, I didnt take measurements, but its @8-10" higher. Over the weekend I towed it over the mountains and back. While towing, I could tell that the CG is up while cornering - but after I got comfortable with it, I didnt notice it anymore. Most of the issues came up while camping. I now need to buy a 4 step to replace the 2 step, and I need to look at additional stabilization. Right now all I have are two screw jacks in the rear, and a single BAL "between the tires" spreader, which was fairly stable prior to the "lift". Now, I'm thinking about adding a king pin stabilizer, and an additional tire spreader.
SO if your considering the dollars involved, be sure to consider additional steps and/or stailizers.
FWIW, my pin weight only compressed the springs 1 inch, and I still have about a 2" difference in height from front to back, with 8" of bed to trailer clearance. Tire heat seemed consistent between the front and rear sets, so I think that a slight "up" attitude is OK.
I've only towed it once with it lifted, and even with the 8" of bed clearance I have, I've come precariously close to hitting several times. You guys that only have 4-6" are, IMHO, living on the edge!!
I do now have the opportunity to add TONS of "Basement" storage... . I'm already concepting a flip out deck..... !!!!!