Thanks for the feedback!
I've usually just set it on the ground to what I anticipate it to be in the air and go with that, but I think I may go with levelling it on the ground and leaving it alone. I expect a bit of difficulty adapting to flying 4 degrees nose down or rotating to 9 degrees off the deck (5 from level) but I see the points made for doing so.
I've always thought of it as abit of a heading bug. You set the heading bug so you don't have to remember XX degrees, and I've always set the ADI for the same reason, so I don't have to remember X degrees nose down. Anything to make life easier.
Anticipating poor altitude control for a few flights!