Ok, since I use Exposé hot corners, I have to leave it not hidden, on the left. I kept sliding into the corner and triggering the Dock. This feels natural. More vertical space, no interference with hotspots or scroll-bars or palettes.
Only thing is, I used to use the dock to remind myself to use the other programs that aren't running.
ADHD? Like "Oh yeah, I have Painter. I should use it now." I'm afraid that a stripped down Dock (of only running apps) might make me forget to do things.
We'll see.