Tip up. I have carried Bob Terzoula's ATCF for about 8 years and have not had a "surprize" experience when reaching into my pocket. I have recently begun carrying a Spyderco Native on my left (also tip up) this has not been a problem (granted this has been only for a few weeks). Both have deployed nicely. I think what works for the user is the bottom line and tip up has worked for me for quite a number of years without having to reach for the band-aids .