It does make a difference in collar height because of the position of the threads in relationship to the bottom spring cup. This applies when running a different length shock end at the bottom, since the spring cup does bottom out on the shock end. Personally, I use TC6 ball cups for ball ends and I cut off 2mm off of the front ones to get the spring cup lower and get my ride height low enough. I should have specified this in the previous post.

While it is true that most people won't notice a difference in handling with the piston height, it does not make the procedure correct. You'd be surprised if you actually measure your shocks with calipers, your variance might end up being 1.5mm between the shortest and longest shock.

FWIW, If you want your car to be at its best, measuring your shock lengths is day 1 stuff. It does make a difference.