I've never been in a 1500 so I don't know for sure, but I have a feeling the ride wouldn't be all that much better. Like yours, mine rides hard on bumpy roads, but is smooth as can be on the highway or decent local roads. Even a 1500 is a heavy truck with truck suspension.
I always see your signature with the "trade my 4.10's for your 3.73's" and I'm with you, I'd love to do that trade. I'd do it but it just seems like too much money for the gears and labor, I've had a few mechanics say it makes more sense to swap a whole axle out of another truck, not sure.
Nice as that Ebay Suburban is, I'm blown away that it's going for over 13 grand. I really wonder why someone would pay that much, too many good deals on these vehicles if you look for them.