this has been done a few times before, but since you're a maker and looking for reasons, i'll chime in again. if you're going to reply here, make sure you state your reasons.
i carry tip up IWB as i find it easy to shove my thumb down next to the handle to get a good grip for the draw. trying to find the top of a tip down with my thumb and index finger is a little more time consuming and if i start to look like my dad as i get older (read getting a gut), it could only get worse. i carry spyderco lockbacks or a GT folder here, so i don't worry about the potential problems that liner locks would have as far as opening. for front pocket, i prefer tip down as i can open it faster and more reliable than tip up.
Daryl, are you trying to get a better feel for what you should put on yours?