The Ruger is very durable. Its grip is slightly greater in circumference than the Smith and wears my right thumb knuckle regardless of the grips I use on it. That is a function of my hand size and may have no effect on you. In the 2 3/4 inch version, it has a slightly longer extractor stroke than a 2 1/2 M66, which can be helpful.
The biggest disadvantage that the Ruger has for me is that the trigger has a "false reset" as it returns to firing position. If you slowly let the trigger go forward, you will feel a click before you can pull the trigger again. The Smith does not have this characteristic. The false reset will only be noticed in very fast double action fire, such as IDPA, IPSC, or shooting at some moron to save your life. I talked to the Ruger people at the SHOT show about it and they said it can be minimized but will always be present. A gunsmith friend explained that it has something to do with the way the Ruger timing works. This was unacceptable to me but you might not notice it. I went back to a Smith Model 66 as a result.
Also, Bill Ruger is no friend of the Second Amendment and his recent statement at the SHOT show point that out again, even if he was "rehabilitated" by the NRA for giving them a million bucks.