How does the damping compare between the air and the coil shock?

It feels like the rebound damping is light and free-moving at slow speeds, but not too fast when returning from deep in the travel. Am I right in thinking it's a relatively linear rebound tune?

Do you offer different damping base tunes for different suspension designs or riding styles?

With the coil shock there is a setting bank for service centres to adjust the base tune via shims to suit different bikes - is the same true for the air shock?

How can I tell what size of volume spacer I have in the eyelet end of the shock? They don't seem to be marked?

Does the firmness of the climbing mode depend on the LSC adjuster position, or is it independent?

You no longer make the single-tube STX shock, right? What do you see as the main advantages of twin-tube over a single tube for an air shock?

Why does the TTX air have the rebound adjuster at the head of the shock while the coil has it at the eyelet?