The Sonics really blew the Payton situation in the Summer when they didn't sign him to an extension, but there was still a chance he would have stayed if Mr. Starbucks had been a little more friendly... No, I wouldn't trade Mason for an injury-prone Allen. I really thought he was the future of the franchise. Payton should have been enough to get Allen.
You and I just view Mason differently. I think Allen is better than Desmond, though Desmond is a good young player. If I'm seattle, I'm very happy I got Ray Allen in return for my future.
Allen is much better than Mason. Mason's not really much of a half court player, since he isn't much of a creator for himself or others.