Here is my .2 cents; if I am on the market for 44 Magnum S&W, my absolutely top choice would be M29/629-3 or -4, Classic DX, period!
With DX models you are getting the most accurate S&W-s ever, tested in factory for accuracy and making 1,5" on 50 yards. Only those receive DX marking.
With M29/629-3 and -4 you are getting endurance package, and also no MIM parts. Earlier dash number or no dash number, no endurance package. With -5 and up, mechanism parts are made using MIM process. Some say that MIM parts are OK, however, top notch custom smith Clements refuses to work on them:
"I am currently only accepting N-frame cal. conversions. I cannot do action work on newer guns with MIM parts. If the back of the trigger has cavities cast in it, then the gun is a MIM gun and not suitable."
Clements Custom Guns
I will take his word as the most relevant statement.