I purchased the M&P 9mmC. Have not shot it yet, but the ergonomics are great. I'm a lefty and the ambidextrous features sold me. I went into Turners Outdoorsman to buy a Glock and came out with a M&P 9mmC.
I cannot load 10 cartridges in the 10 rd double stack magazine (this is California, only 10). I can only load 9 rounds. I'm using a Uplula mag loader but there is no room for the 10th rd.
You might take note that this is one of the revolver sections of the Forum. Try your question on the Semi-auto Forums and you'll more likely get an answer.