It rides way better, firm but not harsh. Totally happy with the 5100's instead of waiting for who knows how long for the 6112's.
I'm not sure to be exact on the top spacer width...I planned on using both top and bottom to get 2.25" but the installer recommended the way I went. Don't regret it at all. The Bilsteins are at the top 1.85" setting.
The truck is actually exactly level at 40" front and rear on drivers side. With the airbags I can easily keep level or raise a bit if needed. I prefer the look I have to adding any height in the rear. The airbags actually raised it an inch due to the minimum 5psi but all worked out.