If you really want some good answers go to the
M&P Forum and read the FAQs. If that doesn't answer your questions, post them but most questions have been asked and answered so do a search first
It is a new design not a rehash of the old. I have trouble shooting all but Generation 3 Glocks. This M&P picked right up and fit my hand. To the point, I may sell my Sig 226 9MM to go to the M&P 9MM. I really like the M&P 40.
As for trigger work, check the threads as I have posted links already to an excellent gunsmith in PA that does a nice trigger job if you really need one.
Only thing I am not real happy with is th magazines. I am sending six of them to me NP3 coated to solve the issue I have. (sand doesn't dump out real easy)
As for the grip, I started with the Large but have settled into the Medium. They change real easy and allow more custom fitting.
Now, what models will be released:
So far only 9MM in full and compact size and 40S&W in full size (a few 40S&W compacts are arriving in some places) The 357SIG is not available yet. I just e mailed three barrel manufacturers to see how much to have one made. I prefer that cartridge to all semi auto cartridges. My friend at the factory advised that they are concentrating on what the LE contracts require before anything else. That is their goal.
The 45ACP model was supposed to be unveiled at the Shot show. Looks like it will be a hot item but we may not see it for a while.
I have about 1000 rounds through mine (not as many as I should but time is tight). Only problem I had was feeding in the first match I shot with it. It was my fault and not the fault of the gun. I was running it a little too dry. It likes a little light grease to run better. (I will be trying the Waller Gun Butter
)
There are holster available from most Kydex benders. Mag holders too. Some of the dead animal skin holster makers have tooled up too.
Check out the M&P forum there are a lot of knowledgeable people there.
Regards,