Good question. Ordinarily, I would have said no, but most of the changes between the 659 and 5906 were for cutting corners (it essentially has no real grip except for the polymer). They made the sights better, but if I had my choice, I'd take the 659. If the polymer grip of the 5906 ever cracked or broke, the entire gun would be pretty much useless. In fact, the first series did have a tendency to crack and were recalled. S&W sent me a replacement, which I put on, but I was careful to save the original. If you have one and haven't replaced it, I recommend you do so.