wow, I never really thought about the safety issue of a 2 vs 4 post lift, that is interesting so many people took that into consideration.
My father has a couple lifts, and he has a really nice 4 post, he has a sliding air jack for the rails {has what looks like an air bag out of a tractor trailer on it}, and he used to work of that lift all of the time, until he got his 2 post. I know "everything" is possible with both lifts, but a 2 post for me is really much easier to do "everything".
For instance, I recently did the lift kit on my JKUR, I was pushing and pulling and banging on all kinds of stuff the jeep didn't budge on the lift, I was working on the front and back at the same time {you kind of have to on that one since the front sway links are the stock rears}, this would have been an issue with a 4 post unless I had two carriages {they are expensive}...
I started that project by pulling the jeep on the lift, ripping off all 4 stock wheels, front and rear bumpers, and the grill. then the tires didnt go back on until everything was done. I had to lift the front and then let the axle hang way down to get the larger springs in, I had to use a ratchet strap to pull the axle straight with the wheels on it to adjust the track bar, all of these things would have been much more time consuming and difficult on a ramp lift.
But lastly I am in a small bay, having a post in each corner would inhibit a lot of mobility in my garage.
I do imagine how nice it would be to not have to bend down and set the pickup points, but honestly, I can use the exercise and it literally takes me less than a minute both sides, if I want to change the risers maybe 2 minutes and I am pushing the button going up. But I lift the same stuff all the time, my vehicles for the most part, and I know where to lift them from, not much thought goes into it at this point in the game.
Even on stuff I dont lift all the time I can get it set up pretty fast, my uncle brought over his camry, the fuel pump was going bad, I pulled it in, got out and set the drivers side {I put leds lights on my lift arms}, wen to the other side and set that side {thats the side with my pump on it} and then lifted it up, before the first lock kicked in I shook the car it was stable and went all the way up, high enough to walk under it and I am 6' 5"..
If someone is buying a lift for storage or just for oil changes and basic odds and ends, or they have super low ceilings, thin floors, etc etc etc I think 4 posts are great. But if you are looking to do efficient service, I think 2 post is a no brainer...