Hmm... mini shock absorber... sealed pneumatic would poss produce more consistency? Less wear over time should spring lose it's tension (? if an issue at all... not an engineer *shrug*)
Know you can get mini-shocks for use with FloydRose style locking trems on guitar... to replace the usual 4x springs... can't recall exact name - ensures trem always returns to same point whether compressed or extended.
EDIT: Tremsetter -
http://www.hipshotproducts.com/tremsetter.htm