Chris,
I have Bose and find it a complete waste of money. You will find that the Boxster cabin is quite noisy and this makes a good, clean sound virtually impossible. I am a Hi-Fi enthusiast and am very much into high quality sound. The Bose in the Boxster is the weakest of any upmarket sound system that I have heard.
I have listened to Bose in an Audi TT, Merc CLK and the Harman Kardon in a BMC 330Ci Coupe. All of these were far superior to the Bose in the Boxster.
I tend not to listen to any music in my car as the engine sounds awesome! At over 800GBP as an option, it really is very poor value for money. Your should also bear in mind that the sound system uses the new MOST digital bus to move sound information around. Once installed, you will not be able to upgrade or change any component.
Some people I know have not spec' d a sound option and have installed an after-market (and far superior) product.
All I can advise is listen to a Bose whilst driving the car! Take a test drive and drive the car as you would normally (slow roads and fast roads) and with the hood up and down. Then decide. Don' t just listen to it in the showroom without the engine running - it will sound good but that' s not how you' ll be listening to it when you get your car.
The Bose does sound better with the hood down - the sound is degraded dramatically with the hood up.
All in all, it was a waste of money for me. The awful CDR-23 supplied as standard (which is actually a bottom of the range Becker head unit) does not help. From what I have been able to gather, the sound is already converted from digital to analogue by the CDR-23 and then given to the MOST bus. This turns it into digital (again!) and sends it to the Bose amps where it is converted back to analogue again. If my understanding of this is correct (and I could be wrong) then this is an utter waste of the MOST bus. The CDR-23 should only read the digital signal from the CD and send it along the MOST bus straight to the BOSE amps for D/A conversion. I do not believe this happens.
Here' s a couple of links to a discussion on Bose from my own forum:
http://driverscar.proboards2.com/index.cgi?board=general&action=display&num=1049801283
http://driverscar.proboards2.com/index.cgi?board=general&action=display&num=1052917869
At the end of the day, only you can decide!