Now, I in no way mean anyone here specifically, I only read a couple of replies. But people are so hesitant to have something like a Cayman for an only car. I don't get it. Need backseats? Fine. Then you wouldn't be comparing these two cars in the first place. You would be AMAZED at how much boxsters/caymans can hold. Probably close enough the huge new 3 series to surprise you. It has 2 trunks, and caymans are hatches. One is a girls car, the other is a sports car. The Porsches quality will not be matched by a 328 either, although it is newer and might be more technically up to date. That's the trade-off for getting a pure sports car for the same price as an entry level BMW sedan. If you are in the position, GET THE PORSCHE!!!!!! You will feel a knot in your chest of pure joy that you don't get in even an M3.
KW V3's, Sparco Pro2000's, Vorshlag CP's, JB4, Heat Wrapped Raceland DP's, aFe stg. 2 Sealed Intake, Miro 111's, Hankook RS3's 225/245 (for now), Seibon M3 CF Hood, Turner Motorsports Alum. Radiator, Big Tom IC, BMW Performance bumper.