I had a 4 post in my big shop, mainly cuz it was there when I bought the place.... I added a crossbeam with a hydraulic jack on it and it became usable for more things. For what I used it for, the drive on was good.... I used it for scaling cars and adjusting suspension mostly. I have a set of roll off platforms for my scales, having the car up in the air was a whole lot quicker and easier then doing it on the floor.

If I was to get one for doing general service work, I would definitely go with the 2 post.