This is a pretty interesting discussion.
I think if LaFontaine and co. came across a candidate that forced them to legitimately re-think how they view certain aspects of hockey, then that candidate would probably be worth a further look.
One of the problems of trying steal someone from a successful organization is that, if it were me conducting the search, I would worry about the assistant gm just trying to xerox those same ideas and implement them with the Sabres. That person might be successful in the short term, but what if many other teams start adopting those ideas or those ideas become usurped by something else, then you don't know if your shiny new gm can adapt to the changing landscape of the NHL.
Also, how do you separate the ability of a general manager from the simple element of luck? Any GM with two functioning neurons in their brain would have drafted Crosby or Mario Lemieux, and I think having those types of players makes a GM's job easier. Players want to win cups so they can make it rain bills at their strip club of choice with the Stanley Cup in tow, so having generational talent can help/makes it easier to attract talent, which may overstate a GMs ability. Granted this doesn't apply directly to an assistant general manager looking to become a general manager, but when you get down to it, when you have a Gretzky or an Orr in the fold, everyone's life in an organization is easier.