Well science or no science... don't bother to wax for year and then try to wax your ski, and you will see yourself. Ptex won't accept any wax and it will feel pretty much like teflon. I have too many friends who ask me to sharpen their edges and wax their skis, and with skis being waxed once a year, ptex >IS< different then with regulary maintained skis.... And it's not about different ptex on different skis... some of them are from same series as my skis are, since I arranged those skis for them together with those I arranged for myself. Ptex pores get filled with dirt and because wax goes in those pores not on top of ptex (wax on top of ptex gets scrapped off), ptex just doesn't accept any wax.
But on the end, everyone takes care of his/her skis his own way. I know that for recreational skiing things won't matter, but with my experience, I still feel like I need to take care of my skis... even if nowadays 1/100sec won't matter anymore, and even if I don't need to protect my "investment", since luckily I still have enough friends to get skis for free whenever I need them. But it's just 20+ years of racing and being WC tech, which hurts looking on skis, for which people don't take care :)