Just a question, how come so many people refer to a 4 post lift only as a "storage lift"?
The differentiation is really not so much 4-post vs 2-post, but "chassis" vs. "drive on". It's generally accepted that it's much easier to work on a chassis lift, since you can easily go wheels off and maneuver around the vehicle. Of course chassis lifts tend to be 2-post, and that also helps because there is less stuff in the way of you maneuvering.
Some 2-posts lifts can be adapted for storage to lift the wheels like a drive-on lift. Typically its better to store a car on a drive-on style lift because the suspension isn't in full droop.
You can do work on a drive on lift, especially with a bridge that can jack the car up off of it. Or if you're just doing simple exhaust work, alignments, etc...
EDIT: Also some people prefer 4-post as they feel that it's safer. I have friends that won't go under a 2-post lift because it scares them. Statistically that's probably true, though I doubt that any properly maintained 2-post will kill you if you are loading it correctly. I'd wager majority of the accidents are going to be maxed out weight and poorly balanced. It's like towing with a truck, the little Chevy Colorado might say 7,000lbs, but would you tow 7,000lbs with it? I wouldn't. Hell even a gasser full size truck will be a burden to haul 7,000 lbs in for meaningful distances. You go diesel HD at that point.
