if you get the angle wrong will vibrate a lot (esp from a standstill), it is a common problem and also multiplied when SOA due to more wrap, i doubt it will work without a t-case drop or SYE. I agree with the anti-wrap bar. For shocks you can relocate the lower shock mounts on top, since you keep the stock leafs should just be offset by the amount of lift (you have to cut and weld new perches anyway). Steering linkage would be another concern, something with the clearance over the leafs if i recall correctly. imo, when you're all done, will cost more than a bolt on SUA kit and be more involved.
I wonder if SOA on stock leafs (without add-a-leaf) in front would make it unstable under breaking (I'm asking, i don't know the answer).
This is why some people do a SOA front and SUA rear. Keeping the rear SUA will make axle wrap a non issue. Though it's at the cost of some articulation. Most Jeeps will have more travel up front then in the rear anyway so it's not a big deal.
Bumpsteer will be determined mostly by the spring rate of the leafs, the steering geometry and the CG of the vehicle. I run rear 5-leaf packs in the front for a bit more spring rate. When I was running 35's I had a lot more bumpsteer. If I hit the brakes while at highway speeds, the Jeep would pull hard as the nose dove. Let off the brakes and the nose would rise and the Jeep would straighten out. When I went to 33's a lot of the issues I had disappeared. Keep in mind that I have a hardtop which raises the CG as well.
There is an issue where the draglink can contact the leaf spring but it depends on the perches used. Rubicon Express's clear fine though. This brings up another issue. If your compare a SOA to a SUA of the same lift, you'll be having a lot of the same issues. Not clearance issues but all the other ones, like brakeline lengths, driveshaft angles, steering geometry, etc... Comparing a SOA to a 4" SUA (off the shelf kit) would be like comparing a 4" with a 2.5". A lot of SUA kits cheap out on things like shocks and use transfer case shims rather then sell you a SYE, which they really should be selling. If you price the same shocks, the same SYE, the same brakelines, etc... The only price difference should be the cost of the leafs vs perches and an anti-wrap bar and the potential cost of labor for the welding.
When I swapped from SUA to SOA up front, it cost me $250. $200 for the springs and $50 for the perches. Oh and $30 for new U-bolts.
