I completed the Boxster Plus test drive at the bumpy Llandow race circuit in S.Wales - i drove a variety of cars ont he day, including 2 S models, one with steel brakes and one with PCCB - i can't honestly say i noticed any difference in the suspension reaction speed/compliance in favour of PCCB. What was obvious was that with PASM in sport mode in both cars there was a lack of traction in the bumpy hard braking area for the last chicane - normal mode had no issues under braking.
I nearly bought a PCCB equipped car from OPC Reading - the sales guy talked me out of it with his comment of Pounds5.5k option when new, deduct Pounds7-8k for resale !
Bear in mind the facelift and DFI engines will be here in September - maybe not an issue with your financial situation, but there will be improvements to engine BHP, maybe 30bhp more !
Then again the RS60 is a nice spec'd car, and if it have the spec you'd go for anyway then represents reasonable value in a Porsche - ditto the Sport Edition models.
When you are sat inside the Boxtser you can't see the outside of it, so just imagine its a 997 body