IIRC, the Chicago PD union president said that around 1,100 officers had P320s as primary duty weapons, but didn't say how many had alternate duty weapons that they could switch to their primary. For those who don't know, Chicago PD officers purchase their own weapons from an approved list of 9mm striker fire pistols (Glock, S&W M&P, Beretta APX, Springfield XD). It seemed like since the P320 got approved, officers were split evenly between P320s and Glocks at maybe 45% each, and the remaining 10% were getting M&Ps with the occasional XD here or there.
In theory, the department should have to compensate officers for disallowing their previously approved duty weapon, but since the FOP has far less power than the Chicago Teacher's Union, the city is basically kicking the can down the road, saying, 'Contract violation? Whatever, go ahead and sue.'
I've seen the ad flyers from your buddy's distributor, and they are certainly aggressively competing for the market share that the dumping of the P320 has opened up. I was a bit surprised that another S&W LE distributor besides Ray O'Herron was allowed to sell direct in IL, but that does just mean that there are two distributors covering the area like with Glock (Ray O'Herron and Kiesler Police Supply in IN).
IMO, the M&P will probably take less adjustment in presentation for a former P320 owner due to grip angle that falls somewhere between a P320 and a Glock. The slimmer M&P grip is also a better choice for the short, small-handed Latinas who've become much more common officers over the past decade.
I view the aluminum frames as a superfluous expense, and prefer polymer. However, the market has responded quite positively to the M&P Metal, and S&W is in business to sell guns at the end of the day. My theory with the M&P Metal is that it saved the manufacturing process and the aluminum sourced for the CSX after the first gen CSX was a bit of a market dud.