I carry both ways and the knives in my EDC rotation are about evenly split. I had tried to buy knives only one way but there were too many interesting knives that I liked so I ended up buying the knives that were set up the wrong way and I like carrying them despite that. When I started buying knives with clips many years ago, the screw-on clips were almost always made for tip down while the molded in clips were manufactured for tip up.
Since I carry both ways it is pretty easy for me to switch. Usually when I'm going to pull a knife out I already have thought about what knife it is and how to draw and deploy it. If I had to pull a knife out very quickly in an emergency I might not have thought about what it is ahead of time and I could fumble, but I would probably fumble anyway. There is not a lot of difference in speed even if I pull it out the wrong way, but there is the possibility with tip up that I would lose control of the knife.
I carry clipped in my right front pocket. Even though I have long fingers, tip down is still faster and much more secure for me. All of my knives have detents on the blades so I don't worry about a knife opening in my pocket. I've been carrying knives with pocket clips for over 20 years and never had one open on me, including my much older knives that did not have detents on the blades. I don't worry about cutting my hands if a blade opens because when I have a knife clipped in my pocket it is almost impossible to get my hand into that pocket, but worst case I could cut my leg.
I do find it interesting that some of the Spyderco models that can have the clip mounted either way come tip up from the factory while others come tip down from the factory.
I read a lot about people that damage screws and liners by switching their clips end to end. I usually just leave mine where they came from the factory, so my PM2's are tip down and my Gayle Bradley is tip up. I have a pet peeve that people will buy a knife, switch the clip, never carry the knife and then try to sell it. If they are going to sell it, why even mess with the clip and risk damaging the knife? And also they will try to sell the knife as "new". If you have messed with the clip, then it isn't new anymore.