I'd agree that he was so consistent that you can't really distinguish career stages based on his location. Per 82 games, he was a 94 point player in Hartford and a 95 point player in Pittsburgh. About 4 of those points shift from goals to assists, which is really not that big a change when you consider the context. He was the same guy, transplanted from a very bad team to a very good one.
He was 35 when he got to Carolina and the league had entered Dead Puck mode, so clearly that part of his career had a different flavor. He was much less of an offensive threat for obvious reasons, and his two-way presence and leadership became really crucial to his team's success. I don't think you can say "better player" but he kind of entered that late-career-Modano or late-career-Yzerman phase where it was more about his presence than about his production.