FWIW we installed a Pro Park 8 4 post lift about 1 1/2 years ago It is tight getting around the posts at times, but it does a great job. The initial intent was to be able to stack two of our pony cars in a single garage stall. It handles that perfectly, but we did have to get special high-lift railing for the sectional garage door to gain maximum ceiling height in our finished garage. I do not recall the ceiling to floor measurement, but suffice it say that we have barely 4" of total clearance of the stacked cars (2 " of the bottom car roof vs lift cross brace, and 2" top car roof and opened garage door. I knew it was going to be tight. But, it works fine. No paint has been scuffed on any roofs (yet)...
I had hoped to be able to use the lift to work on the cars off the ground, as a secondary hope. That worked out really well. But, in order to make the most of the 4 post life getting wheels off the ground, or lift ramp, I bought the option rail mounted hydraulic jack. I found two photos of the lift ramp where you can see the center hydraulic lift, if you look carefully. attach it. Well worth the additional money. The center hydraulic lift unit had arms that extend out toward the driver and passenger sides of the car, and have some lift extensions with very hard rubber to contact the vehicle underbody. In some cases those ears and extensions did not give me the lift to get the wheels off the ground when lifting from the unibody (not from the lower control arm). I was able to put some pressure treated 4" x 4" wood blocks between the lift pads and the underbody, which works out perfectly.
There was one time I had to replace the Shift Shaft and Arm assembly on an AOD I swapped into our 73 Mach 1 (THAT was a fun project!). I was able to get to the AOD just fine when the Mach 1 was up in the air on the lift ramps, but reaching up overhead for long periods of time was giving me grief (side effects from life saving brain cancer surgery). While up high in the air I drained the AOD tranny oil. Then I lowered it until it was about 1 1/2 - 2 feet up in the air, and waited for the 4 posts' safety locked clicked into place. As a precaution I put some jack stands under the car. I was then able to use a floor creeper to get under the car and swap out the Shift Shaft assembly and installed a new, highly adjustable shift shaft from Summit Racing (Lokar PMA-PASS53104) while laying underneath the Mach 1 very comfortably. The entire operation was made far easier with the car being easily and safely lifted using the ramps on the 4 post design.
I have now used the lift for several repairs on our cars and on a neighbors Subaru (brake job), and feel this is one of the best investments I have made in tools in a very long time. A two post life may have been more practical, but I have no idea how thick our concrete floor is, much less the quality and strength of the concrete. With a 4 post life that is not an issue, it is rock solid whenever the posts are placed on a level floor surface. Also, I can relocate the 4 post life easily if ever I want to do so.
Four post lift, not one regret. But, I strongly suggest getting the center hydraulic lift option, which has a housing that slides back and forth on the left and right side inner ramp rails. The center lift is very heavy, best to get it set up when the lift is first assembled. Also, despite how good you may be at assembling equipment, I suggest having the reseller install and set it up, and show you how to use and move it. You will need a 110 volt outlet nearby for the electric motor that handles the hydraulic powered cables to lift and lower the unit lift ramps.
