If you've got the cash, I say go for it. I am a poor man though. I will buy these very soon (Sumitomo HTRZ II):
http://www.tirerack.com/tires/tires.jsp?tireMake=Sumitomo&tireModel=HTR+Z+II&partnum=05WR7HTRZ2&partnum=54WR7HTRZ2&vehicleSearch=true&place=1&index=1
This tire comes recommended by Jeff (Tool Pants) a long-time Boxster owner on this list and RennTech. I think I'll give them a try considering the Kumho Ecsta MX's I have on my boxster now have just 10k on them and the fronts are cupping already.
Just remember that if you buy unidirectional tires, you can "rotate" them by knocking the rubber off the rims and moving them to the other side every 2-3k when it's time to have them balanced (which seems to be a constant need on my car anyway). This can double the life of the tire if you do it consistently.