I think there is truth to the story's you will hear.
I have seen more used Smith&Wesson .44 mags with problems than any other revolver make/model in my 25 years of interest with them.
Loose tolerances, endshake and timing problems with many a 29-2 and early 629's.
The revolvers were used and there was no way to tell how many and what type of rounds had been through them.
Then there was the problem also of cylinders unlocking during heavy recoil with heavier and stouter loads.
Smith addressed this problem with the full endurance package introduced on the 629-2 E and the 29-4/-5. Also they made the cylinder bolt stop notches larger to prevent the unlocking problem.
So the desirable and strong pre lock .44 mags will be the 629-2E,629-3 and 629-4. The 629-5 is good but has MIM parts but no lock.
In the 29 series there may have been a short run of 29-4 with the full endurance package (not sure, can't remember) but the 29-5 and 29-6 are pre lock/pre MIM with the full endurance package.
One must remember that the N frame has a removable side plate (makes it less rigid) and was originally designed as a non magnum .44. More modern frame revolvers like the Ruger and Dan Wesson are stronger (also bulkier,heavier and less visually appealing IMO.)
In all fairness though I have never seen a used 629-1 with problems.
Its my opinion that anything that needs to be done with a .44 mag can be done with the N frame with the endurance package, think 300 grain hard cast at 1200-1300. If one needs more power it makes more sense to go up in caliber (.454casull,.480 Ruger ect) than to hot rod the .44 mag.