I set mine based off my ungeared weight and then adjust if necessary. I've never weighted myself all geared up..
Last time I let a shop mount and set my bindings they set them to the level lower than I requested. Went home and bumped them back up to my usual 8.5 and that's the year I started mounting and setting my own stuff. I started with the charts and then tweak them as needed for how and where I ski, groomer skis get about a 9, and everything else gets between 8-8.5 depending on the binding on the ski. It has been a very long time since I had a pre-release but every time I've crashed significantly my bindings have released properly, which is exactly how I want them to be.