To me the wind deflector affect the look of the car, and the wind is part of the deal w a convertible. At any speed I don't really suffer from the turbulence.
Space, well use bag rather than hard luggage and you will be able to stuff a fair bit in it, especially behind the sit.
The sit are fairly comfortable, the driving position is good especially if you drive relax.
The ride quality is what it is, a italian convertible. I guess a strut bar is an improvement, but it will shake and vibrate and the road. Again to me this is part of the "charm" so I try not to care so much.
I guess buying a convertible is like buying a MPV, you have good reasons to do so yet you know that there is also a down side.
Saab 900 s convertible is a very good car, with a lot of room for everything and more, the turbot supply you with a bit G force, but then again look at the spider then at the 900...
There is no competition.
So go ahead buy yourself the spider and enjoy...
You can get the 900 when you will closer to 60