My experience is that If you have good acoustics in the room you are recording, placing a stereo microphone at arms reach distance, will give you nice natural live sound and reduce the need for reverb effect and mixing. On the other hand, if the room has feedback noise and\or poor acoustics, you are better off using mono close microphone and adding reverb effects for depth and stereo effect. As far as I know, most professional studios record sax in mono with high quality reverb, so I don't think recording sax in stereo is that important, even if you have a good room...