I can not speak on Glock's. I have never owned one but I have shot plenty of them. As for the SR9c, I love mine and have had no reliability issues with it. It happens to be my wife's favorite of the hand guns that she has fired. Actually her first time firing a gun in 10 years was with with my SR9c and after 3 rounds she was shooting 9 and 10 rings all afternoon. The manual safety is not an issue, I leave it off and have never had it accidentally knocked on. My only gripe, and this is a very personal thing, is that it is not available with factory night sights. However I will be ordering a set of Meprolight's for it soon. Otherwise I find it hard to fault the gun in any area.
Did you show your wife an M&P9c the compact is usually a good choice for woman and people with small hands. It's also a very good option. Also have her look at the FNH FNS-9.