The Dmaxstore XD tie rods (not the kryptonite parts) don't have a better warranty. If you want lifetime you need the kryptonite parts and they're +$100 over Rareparts.
It's complete overkill to spend $700+ on a kryptonite centerlink and tie rods, let alone $1200+ for the "stage 3" kit. If your front end is wore out, it may justify itself a little, but for how many people just throw on a set of sleeves and a DHD brace and have excellent luck, I don't see the point.
Have you gotten on the rareparts website and read their warranty? The XD is $20 cheaper with a better warranty.
As far as kryptonite I would prefer a straight centerlink over the kryptonite centerlink. You're not gonna break an xd so unless you plan on keeping the truck I'd save the pennies.