tough choice!
I already own an M9, and love it. Having said that, I think the vertec is an improvement over the standard 92 series. In my hands, the vertec feels much more comfortable, since I have average to smallish hands. Also, there is a light rail on the vertec that is a nice touch. Your decision really depends on the prices of the two guns. Around here, Vertecs are kinda pricey when compared to my M9, which, by the way, came with a 15 round mag. Either choice is excellent, and there is absolutely no way you can go wrong with either!
Pat Brophy