Yeah, sounds to me like a light spring on the hammer. All my Smiths hit hard. Luckily, it's easy to replace if you're familiar with the gun. This illustrates why I do a complete clean-up and tightening on every gun I acquire. Why leave anything to chance?
And I'm no stranger to screws that back-out on my revolvers. In fact, my Blackhawks are the worst offenders with that two-piece frame and five screws holding it together. Typically the Smith's cylinder latch and front sight ramp screws are the worst. I found that tightening them while the gun is hot gives the best hold. The cylinder latch on my 686 has stayed put since, although I got into trouble with a sideplate screw on one of my Dan Wessons, as I detailed in another thread. If I was smart, I'd just lock-tite them with the blue stuff, then hit the screw head with heat when I wanted to get them out.
I don't think wear makes much difference unless there was real abuse. My 686 has been beat on, but my pampered M67 and M25 had the same issue until I corrected it.
Sure the S&Ws have their idiosyncrasies. But I like to keep the important things in mind. I've never seen a bent frame on a Smith, and I'm not sure I'd want to trade down my 686 for a GP100 with a smaller cylinder. If I need more power than that will handle, I'll reach for my Dan Wesson 357 Supermag.
But I'm not trying to pass judgement on Ruger revolvers. I have two and that's still not nearly enough.

I recommend a careful inspection of any revolver that you buy, and don't be afraid to haggle when you see that things need fixing, but be polite about it. So far I've had good luck, whether in mechanicals or actual performance. I still regret that 629 DX I passed up many years ago. Man, I couldn't even touch anything like that now for $400 NIB.