I've been reading reviews online for winter tires - however, I think the best opinion will be from a Boxster owner that has actually used winter tires.

What do you folks recommend for snow/rain conditions?

 

Well, the best option is don't drive in snow/ice.... I say "Save the Boxster".

Otherwise, contact www.tirerack.com I'd also get a cheap set of "winter" wheels to have the winter tires mounted to. Plus, I'd go to a 17" wheel vs. the 19" on the RS60 AND I'd go with a narrower tire width to keep all the crap and chips off the fenders/bumper. Plus a narrow tire will do much better in snow vs a wide "ski like" tread width. Tire rack will work with you to keep the tire diameter the same as you have now.