Tip up for me, please.
I can deploy a tip-up blade much faster than a tip down, because I don't need to waste any time changing my grip. Fastest possible deployment in emergencies is a much more important safety issue for me than the distant possibility of an occasional minor cut requiring a few stitches. (I've been carrying tip-up knives for 9 years, and I haven't gotten a cut from a knife opening in my pocket yet.)
Tip up also allows for putting the clip closer to the end of the handle, since it doesn't need to be near the pivot, thereby allowing for the kinfe to ride as deeply in the pocket as possible. This draws less attention, and also is less prone to catching on things. A well designed clip on a tip-up knife also fits in your palm and adds to the comfort and security of your grip.
I agree with SharpBits that you should make the knife with the options for both tip-up and tip-down, as well as both left and right. (By the way, I'm ambidextrous.)