My own requirements were:
I think I've made it work... ;)
You may experience some wear on both the threaded rod and the nut (especially if you're using z-lift a lot). You can tell when the Z step motor start to skip step and have a hard time lifting the Y carriage.
I had to replace mine after 6 months of almost daily use and went to stainless threaded rod. The price is ridiculous (2 EUR) and they are far better quality than the original. Nuts should be changed accordingly. Also no need to exaggerate on the torque of the upper nut.
Added some example of the Z quality obtainable with the help of this add-on.
You need to check the clearance every now and then. If they get too loose, they will have no effect. I had to recently tighten them again... It really make a difference on the quality of the part and eliminate what is sometimes taken for "Z-wobbling".