Perhaps it depends on what your goal is for the vehicle you're lifting. Personally, I won't be using mine to it's full potential so the use of a spacer in addition to Bilsteins works well for me. I did consider no spacer, but after seeing so many builds here using them, I thought I would give it a try.
PS, just for verification, are you able to see the pictures I posted? I received a PM saying they can't be viewed, but I see them on my end.