The aftermarket UCA have one primary purpose, to allow alignment at 3" lift height.
If using them for a lower than 3" lift height, but higher than ~ 1.5", they work fine, and do add about 2" of down travel, which is nice.
If you add the new UCA, and crank them up to ~ 1/2" upper stop clearance, you essentially have a FRONT ~ 3" or more lift.
You want the nose to be about 1.5" lower than your butt for the truck to work best, and that's pretty much the OEM rake....so when people do a 3" SL, they raise both ends 3", so the front is still lower by the same amount relative to the rear.
Newbs who want the truck "Level", in addition to bringing joy to those who sell newbs "Leveling Kits", simply lift the front ~ 1.5" more than the rear, eliminating the rake.
So, if you use new UCA, after maxing up your butt, just raise the front until you have it ~ 1.5" lower than the rear, and you're good to go.
Remember, the "Perfect Suspension" allows the tires to go up/down with the undulations in terrain, while the truck stays dead level and stable. Too little up travel left means that corner of the truck is tipped up instead of just the tire. Too little down travel left means the truck tips over, down into the hole, instead of just the tire going down but the truck remaining stable, etc.
With the new UCA, you get ~ 2" added wheel travel. If you use it all to make the front higher (Uses "pre-drooping" to raise ride height), that leaves too little DOWN TRAVEL left to follow uneven terrain....so that front corner of the truck will be tipped down at depressions/holes, instead of just the TIRE drooping down while the truck stays level. If you use the total wheel travel more proportionally, you get enough up/down travel to allow the truck to glide along in a more stable fashion.
AC's UCA are what I'd get if I needed new UCA at this point.