air suspension? Its great. YOu have a a huge range of adjustibility.
Think about a fork for a minute. You have to buy springs according to your weight, and of course factor in riding styles/conditions. With my SID (air), all I would have to do is pump a little more in with my shock pump if I gained weight. When I commute, i pump it up and put on the lockout. Then I can manipulate it again for when i hit the trails, air is the way to go in my opinion