Looking around their site and trying to compare prices with M&P's, it seems the Smith's at Whittaker's, at least those that I looked at, all had ten round mags while the M&P is a fifteen round gun in 9mm. I wonder what's up with that?
They appear to have both 10 and 17rd guns. Most dealers who are on the internet do. That's so they can sell to customers in communist states. Many times, they'll overorder and have to sell the 10rd guns for less. After all, why get a 10rd G17 when you can get the much smaller G43X with the same capacity.