The S&W will easily handle .44 magnum amm all day long, they just aren't designed to handle the ammo that is made even stronger. You wouldn't have any problems with the S&W 29 or 629 with full power .44 magnum ammo but if you want to shoot the stuff that is pushed to maximum power from Buffalo Bore, Corbon and such you'll have to go with the Ruger. Very few .44 magnum shooters ever shoot that super ammo because the recoil is brutal and because standard full power .44 magnum ammo is already very powerful.
You won't go wrong with either!
If you say so, but one of my older 629's has been eating my handloads since the early 90s, but it did go back to Smith for it's second barrel after the first 8,000 rounds (1997). Get a PRE-LOCK S&W 29 or 629 and enjoy it.