I know we drive faster than a lot of jeep drivers on here so I always throw in that caveat on these gearing discussions. With that being said, 4.56s with 39s is still geared lower than a stock sport/sahara with 3.45s and 32s. 4.56s and 37s is almost identical gearing to 4.10s and 33s in a stock Rubicon. Having run deep gears, I wouldn't go into the 5.xxs unless I was building Dana 60s for 42s or larger in a JL.We sound similar. I like to try challenging lines, but I’m a finesse driver, and don’t like to hammer my rig.
I know guys are running 40’s in the gladiator in stock axles (same ones the XR has) without many issues.
Looks like 37’s or 38’s are next on my list of upgrades.