Tip-down is the proper way to carry IF you want to draw the knife and open it in the fewest steps. The Skirmish was designed by Neil Blackwood who still makes it (apart from Benchmade). All of his knives are made tip-down carry.
I have a mini-Skirmish and love it. Slim (in the waistband carry), tip-down (!!!), large S30V blade, nice, tight lockup.
I received a BM Rukus for CHristmas. It's clipped for tip-up carry. I had to make a sheath for it and remove the clip. Tip-up is fine, I'm just so used to drawing the knife and having it ready to open that I couldn;t adjust.