I'm not surprised Danny stayed away from him, I don't think he'd be the best locker room guy when he's a backup.
When you take a risk with Marbury, I think it's safe to say you can sign Rafer Alston.
It looks like Rafer was really eager to play for us and had no problems with the playoffs series of last year and his slap to Eddie, so he probably wouldn't have caused any chemistry problems.
He caused problems in Orlando and in Houston, why wouldn't he cause them here?
Besides the Marbury signing didn't work did it? I recall several quotes saying that he was a distraction in the locker room a couple of times and Doc had to say something to him.
What problems did Alston cause in Houston? I'm not aware of it but if I recall the Rockets decided to take a gamble and make Brooks their starting point guard by shipping Alston out of town. The gamble worked pretty well!
As for Orlando, I remember Alston creating controversy during the Finals but Van Gundy did a terrible management of his point guards by playing Nelson when he was getting back from injury and totally out of rythm with his team, and to the detriment of Alston. It basically cost the Magic the Finals, so I can't blame Alston for criticizing his coach about it.
Also, you have to consider that Alston was totally aware of what his role and minutes would be had he signed with the Celtics, and he seemed (according to the article) genuinely OK and excited about it, so I don't see why he would have caused problems, knowing his limited role from the start, and having the will to fulfill it.
As for Marbury I didn't read anywhere that he caused problems at times, do you have some article about it? It's interesting.
Plus, the biggest difference between Alston and Marbury is that Alston is not as crazy as Marbury, and he has played in the NBA for the past few years, rarely hurt, and always contributing, so it wouldn't be as much of a gamble as bringing a guy who didn't play basketball for one year.