Concerning storage, I think a 4 post is best simply because it's a bit more straight forward concerning getting the car off and on, there are no points of contact with the car (some highly detailed undercarriage cars can end up with small paint scars, etc from the two post lifting arms, especially if stored on them for long periods of time) and ultimately the 4 post offers a more stable platform in the event the car or lift gets nudged hard, earthquakes, accidents in the shop, etc.