** Looks like I'm living in a time warp. You have already made your choice, but that post didn't show up until after I had replied. **
I think you will be pleased with either one. I was smitten by the appearance & feel of the Python back in the early 1980's. I have only owned my Python for about 6 months, and love to shoot it. When shooting SA, I have to remind myself to be careful, because it seems that all I have to do is think about it and the gun goes bang. My first shot at the range yesterday was that way.
The Smiths are excellent guns, and have a little different feel in DA. Ideally, you should try to shoot both and see which you prefer. You mention shooting leagues. If this is fast action or outdoors, get the stainless S&W. It would be a shame to ruin the bluing on an old Python by dropping it or having something else happen to it. The original grips alone are in the $250-300 range. If it is indoor target shooting, you could go either way. The 627's additional two rounds are nice (8 shots vs. 6 in the Colt).
If this gun is to be a sentimental keeper from your wife, I'd be tempted to go with the Python just because they are more "special" (rare, out of production, coveted, rising in value). While there are many people trying to replace their recent 401(k) losses with the sale of their safe queen, there are still Pythons to had at reasonable prices. I paid $750 for mine in 95% condition. The challenge will be waiting for the right one to come along. I bought a couple of revolvers while waiting for the right Python, so it might be "easier" to go to your favorite gun store with your wife and let her buy you the S&W.
Good luck in your quest. You really cannot go wrong either way. Let us know what you end up doing.