I have 2" spacers on my 1999 Sub K2500. No problems after 60,000...a few others on here have them as well. The Sub drives much better with them especially if the road has grooves from heavy vehicles..
No problems that I have heard. When I rotate tires I am just more careful to nip the lugs up on the back with incremental torque and star pattern (I use several more steps than front tires and wiggle the tire some too at first contact just contact then nip and repeat. I have steel rims and the lug nuts cone will pull to center pretty good. I had a set of alumimun wheels on a '78 that were lug centric. The lugs were not coned but went through the rim like a shoulder bolt part way. The tires were 36" and a real pita to mount and get the lugs started.
I can't tell much difference in ride but it looks a lot better. Stock the tire looks sunk in and doesn't fill the wheel well as nice. The truck looks more symmetrical now and maybe a little more beefy.