CJ,

I think what has caused some to speculate that you have a commercial model is that there is no lanyard ring. I noticed two things in your picture. One was the "Made in USA" on the right side of your frame; I know the Brazilian contracts had this, but am unsure if the commercial model did. I know the original issue Model 1917s did not. Check and see if the lanyard ring hole is present, but I am also unsure if the original commercial issues had a lanyard ring or didn't, but I don't believe they did. The other thing I noticed is that the side plate does not look to be original. S&W polishes the sideplates to the frame, back then and today. You can see that the bevels above the trigger guard from frame to sideplate do not seem to match; I looked at my 1917 today and could see that the match was perfect, and so am suspect your sideplate is original. The lanyard ring (or none) should also be an indicator. It may simply have been removed. Whichever you have, it's a keeper, whether or not you decide to refinish it or not is up to you. I also suspect it has been refinished as the inscriptions look like they may have been polished at some point, in which case refinishing it would not be a big problem to collector's value; have a good gunsmith look at that closely. If it does have a replaced sideplate, that could also change it's value quite a bit. Are you sure the ejector rod is bent, or does it just need to be screwed in all the way? A friend of mine has a Brazilian, and the ejector rod likes to unscrew itself after some firing, which causes binding. Some disassembly and cleaning remedied the problem easily.
Quite a few people prefer the Brazilians as they were supposed to be heat treated and the original M1917s were not. Either way, I think you got a good deal and have a good shooter on your hands. I am a big fan of the 1917s, and am happy to have one of my own. Although those service grips are a lot easier on the hands, I really like the period grips; you can find repro's everywhere if you are interested.