i have OME 3.5" leafs on my NP231 auto 2001 xj with no T case drop and no SYE, i was expecting my teeth to rattle out on the test drive after the lift but i honestly only picked up a SLIGHT seat of the pants vibe from about 45-55K, thats with the old stock U joints with 180,000 kilometers on them.
IIRC my drive shaft was sitting at 15° right after the lift and my T case to pinion was within 2.5°
things have smoothed out more since i put some K's on it,and i intended to do a SYE anyhow, but for someone to just jump in my jeep and drive it, i bet money they would never say anything about a vibe. its that faint.
the whole idea of a T case drop does not sit well in my stomach, especially with my low pinion front end.