You have me somewhat intrigued here.
I use a DaKine XT Seat, and AFAIK the hook height is the hook height.
I've never managed to change my hook height.
Sure, I can cinch up the top straps and the hook might ride slightly higher (until I hook in
and it puts pressure on the lower straps.
Or, conversely, I could cinch up the lower straps, and the hook might ride a little lower (until I hook in and it rides back up.
My XT Seat goes on in the same position every time I use it.
My boom height will change a little bit depending on what board and rig I'm sailing, but
for smaller narrower boards (< 110 liters... sail sizes < 6.0 m2) I mostly use a WH waist
I like my boom just at chin level, except on the smaller boards where it dorps down to about shoulder level.
The formula guys all run very high booms (like forehead high) due to the width of the board and sail sizes needed for formula racing.
I'm not sure exactly what you are feeling here.
If you Exo WS 80 is an 80 cm wide slalom board, what sail sizes do you use on that board?
Is your Starboard 160 a 100 cm wide formula board?
What size rig did you move from the WS80 to the F160?
I'm still a bit puzzled.