I know you guys are gonna think I'm crazy...but when I put my BL on my 03, the ride did change some. I'm not the only crazy one either, many have said that. So to the OP, you heard right.
I know I know, its a body lift, its has nothing to do with the suspension. But you add 3" of solidness between your cab and you cushy cab mounts...it will make a difference. Nothing like adding a rough ass suspension lift...but it did make a difference in the ride.
To the OP...do the 3" body lift, I did one and never looked back. Just DON'T use the tire jack that comes with the truck to insall it. That WONT work. Get you a good floor jack, some 4"x4" post, hand full of tools, and get it done. Just read the instructions and don't skip any steps and you'll be golden. If you can change oil, tires, or brakes, you can do a BL. Most companys that sell body lifts have a PDF file you can download...do that, read the instructions, if its something you think you can do, then go for it