I'll talk longevity of the Clayton arms. I have a set that I originally installed on my 07 JK and then moved them to my 12 JK. 15 years and about 130k miles later I just rebuilt all the rear Johnny Joints because I was hearing a squeak. 3 were in perfect condition and probably didn't need to...
I have always set the rear pinion slightly lower at rest because the pinion will lift once you put a load on it due to torque. Hence, RockKrawlers picture is close to the way mine is set (I'm a little less than 2deg). My JK on a clayton lift has run this way for 9 years.
Ron
Be careful, my buddy did that with a brand new C8 corvette... parked it in the driveway, went with his buddies to New Orleans for the weekend. She woke up and called him pissed off about the new 'vettte in the driveway (she hated 'vettes). He now drives a really nice Honda Odyssey to work and...