The previous post hit it right on the head. Although I've owned a S&W 29 for 30 years and shot thousands of full house 44 mag loads out of it, I've never had a problem with it 'loosening up'.
I would say get whatever feels best in your hands. Its like either buying a chevy or a ford. The choice is up to you. Both are good but and will last a long time with proper care or you can also have a problem with either.