Need help -- get Nitto Invo tire, or Michelin PS2 at twice the cost?

[Spy4cia]

I've got a 2007 Boxster S which I've been thoroughly enjoying for the past 3 1/2 years. Time to replace the rear tires. So far I've always replaced the tires with the Michelin PS2's. A friend has highly recommended I try the Nitto Invo at half the price (and he says the same performance.)

At www.discounttiredirect.com the two tires both get four out of five stars rating.

Also, I'd be replacing the rear tires ONLY, as the front tires still have lots of miles to go!!!

So what say you all?????