There is zero difference. Being bothered by a little hole on the side is just a bit OCD. You don't notice it at all hardly on a blued, as you do on a stainless anyway. MIM on the other hand, is just another way of manufacturing a metal part and it has been used for a very long time now and improved to very high quality standards to the point that the parts of most reputable companies, especially that of S&W, a name that has always stood for quality, now match, yes match, forged parts. Forged parts can have imperfections as well and there lies the double edged sword of the human factor. Could MIM parts sometimes be fit and finished better? Yes. That is the only difference.

Again though, S&W always strives to put out a beautiful, and more importantly, strong product and their guns are still the absolute best both yesterday and today. Times have changed though and so has the amount of times guns are used. Now for fun and recreation/competition more than at any other time. You want an old one that doesn't have the modern "Endurance Package" then suit yourself. It's fine if you only plink once in a while with lighter loads and sit it on a shelf to collect, but if you are a regular shooter then you want a newer one. Tighter tolerances, stronger lockup, stronger trigger and hammer pins, stronger heat treatment on the yoke. All of this you get with a newer one.

Sorry but when I am holding something that could explode in my face and blind me or blow my hand into pieces, I don't care to go on hope that a 40 year old gun will hold up to modern ammunition, modern shooting competition or recreational shooting for that matter. This new method of manufacturing MIM parts is here to stay. It is just a new way of getting to the same result.