Check out cabelas; last time I checked, they had M&P in FDE in stock. If they don't anymore, there are some places they will cerakote whatever color you want on the frame.
Another idea I would suggest is to use paper targets so you know where your misses are going assuming your use a large enough paper target. Steel targets are tough to determine where your misses are going.
Agree here as I too am right handed but left eye dominant. With handguns, there is no issue; with long guns on the other hand, the long gun must go on the left shoulder as it's easier to train your hands to shoot off your left shoulder, than it is to train your brain to become right eye dominant.
Although the M&P changes are supposed to work, you may get some FTE issues and some FTF issues depending on the ammo.
Generally speaking, the 9mm will send a lighter bullet at approximately the speed a .40 s&w does. Therefore the force on recoil spring will be less when you converted to a 9mm...
You should be ok with the blackstrap mixing. On the low powered loads you are right in that they may not cycle the slide. If they aren't too many rounds, it may be ok to use to practice malfunction drills... Just a thought.
Although I like having the thumb safety on my M&P, I wish it was smaller than the big paddles-looking safeties. I like the size of the thumb safeties the Ruger SR-series have. Do you know of anyone who has swapped out or reduced the size of the M&P safeties?
The M&P shield is another example...
My guess is the expected lower demand and consequently the lower volume of sales would drive the price to be higher since manufacturing would not reach a volume high enough to realize efficiencies? Again, just a guess.