A sunroof coupe will not be as enjoyable as a convertible for the "open air" experience. Also, check to see how far back the sunroof is located in the roof.
A bit Apples Vs Oranges here but, my wifes A4 sunroof was set pretty far back.. Far enough that I couldn't really see out of it, but I did get to enjoy the noise of it being open. In my 911 (1978) the sunroof was so close to the windshield that I could see up and out of it. Made the car feel more open than it was.
To me, the open sunroofs of todays cars are just noise boxes. You don't really get the sun/warmth benefits of a convertible but you do get enough wind noise to make it annoying. Full top down motoring is nicer than a compromise. While you can't swing it now, maybe the better compromise is a 996 Targa
Going from a Box S to a 3.4l 996 isn't too big a jump, performance wise, but you will notice it to be a bit quicker. Also heavier. And with a greater rear bias.
Just test drive the dang thing!