It's usually the pinion gear that becomes the weak point as the gears get numerically higher, it gets smaller in diameter. Having said that, I ran 4.88's with 36" TSL's on my old YJ with Dana 30 front/high pinion D44 rear...the rear is an old Currie axle, the high pinion was a good idea, bad execution as it works the coast side of the gears. For my application it met my needs as I had done a spring over axle (SOA) conversion on that rig. My driveline angles with a conventional low pinion rear axle brought the suck. My current '05 Rubicon is running 5.13's in the stock Dana 44 housings with metric 35's.
Another consideration with drastic gear changes is your driveshafts themselves. We learned this the hard way with our Jeepspeed car. We decided to run 7:1 gears in our pigs for a couple of races, the first race in that configuration was the three day Vegas to Reno "The Hard Way" stage race, followed by our next MDR race. In both races we tossed our front driveshaft and pole vaulted the car over it destroying the transfer case. We couldn't understand what the issue was. After talking to the guys at JE Reel (our driveshaft sponsor), we realized that the front driveshaft was not of sufficient strength (tube diameter) to allow for the faster driveline speeds with the numerically higher gear set. Essentially the driveshaft was spinning fast enough that it bowed in the center enough to pull the splines apart. Who knew...expensive lesson.