A few corrections...
As to old vs new - that's up to you. I'll take recent/new - in SS, ie, the 629 - for easier care and the insurance of the endurance enhancements. As to engineering changes, the 629-3 ('89) had the 'endurance enhancements'. The -4 added the topstrap being drilled/tapped for a scope mount, if wanted. The -5 ('97) subbed both a MIM hammer and trigger. The -6 ('01) added the Infernal Lock (IL). My 629's are, both the 4" (SKU #163603) and 6" (SKU #163606), recent (Last 5.5 yr) purchases and 629-6's - like current new stock. They are fantastic - with great triggers. One got lighter effort Wolff's when it was new - I can't tell which now! They weigh 41.5 oz & 45.5 oz, making the 4" production 629 2 oz heavier than a 629 MG - and .5-1.0 oz heavier than a 4" 686/GP-100. BTW, my first .44 was a 629MG - which I replaced with a standard production 4" 629. The added two ounces gets you a bit more mass out front in the tube, both a larger hammer and trigger, and a RR/WO sight set vs the MG's blk/blk.
Want to hunt? Replace the rear sight on the 6"-er with a Weigand rail, add some Weaver rings, a 2x28 scope (Weaver H2 shown), and the S&W/Hogue .500 Magnum monogrips with some 'real' Magnums - and let 'em rip. I don't hunt - it was fun like that as a 100yd plinker - for a while - then back to my favored iron sights.
My 629's are really .44 Specials - like their 'real' .44 Special siblings, see the wood grips below:
I agree - the .44 is a reloader's dream. Start with shorty - and very mild - .44 Russians - go to mild to mediocre .44 Specials - then to real .44 Magnums - all in a 29/629. Just heed my advice - clean the chambers well after shooting short-cased rounds
before loading .44 Magnums. I mainly shoot my wimpy .44 Magnums, which would embarrass Elmer Keith... he'd load .44 Russians hotter! Funny how things change as you age - my first DA capable revolver was a then recently introduced .454 Casull SRH. My last two purchases were J-frames - a 3" 60 Pro, which will likely never see a real .357 Magnum, and a 3" 63 (.22 rimfire). I answer to myself... and I am happy... need more pink grips, of course...
Now, if you don't reload - but still want a big bore - an affordable to feed one, that is - get a 625JM, some moonclips, and enjoy .45 ACP's!
Stainz