I am enjoying my M&P22 so much that I'm now shopping for a full size M&P in 9mm. Since I'm new to this scene, I thought I would ask advice from you enthusiasts.

Are there any issues from older models that I need to be aware of? (Runs of serial numbers I need to avoid, etc.?)

Sounds like S&W has made some recent improvements - should I simply order a new one since I'm in no hurry?

One of my local shops has a 9mm Pro in stock. For those who have shot both, is the Pro trigger nice enough to warrant the extra expenditure, or would I be better off with an Apex if I was going the custom/extra route? (Of course, if this is the 5" Pro, I may jump on it for that reason - haven't seen it yet.) The upgraded sights on a Pro may not be an advantage to me, since I think the back blade is all black (?), and my aging eyes don't seem to perform as well without three dots.

I welcome any advice. I know things like triggers are a very personal preference, but just trying to gather as much information as possible since I have a number of options available. Thanks in advance!

I have a newer model and it shoots great,
and the trigger isnt bad at all!
Maybe mine has the newer parts in the gun,
but I don't know.
I think you should go dry fire an m&p9,
and if you dont like the trigger go for the pro.
Also your shop should be able to order you a
newer model from their distributor.

I did dry fire a used M&P 9mm at a local shop, and had no complaints about the trigger pull. No idea how much it had been used though, or how old the model was.

I'm sure these are all minor differences, and I'm not an experienced enough shooter to be very discriminating. Just trying to learn as much as I can before making a decision, and to make the best investment towards something I'll be happy with long term.

I'm mostly concerned with knowing if there were any specific problems with older versions, etc. I know these pistols have a good reputation in general.

I'd welcome any other advice - thanks.

Well if you want to check how old the gun is
usually the shell casing's date that comes with the gun
is around the time the gun was made or you can look
on the side of the box under the SKU number and it will
give you a list of number
EXAMPLE:
0092 that means it was made in 2010 on the 92ed day. So
1-2011
2-2012 etc. etc.

I was going to suggest the same thing on the age of the pistol. As far as issues with older models, guns made before 2010 have a smaller diameter spring and plunger under the Sear that can cause some trigger issues. I have the newer models so I have not had any prolems but I think S&W will change them out for the larger ones if you ask them. A buddy of mine has a newer M&P Pro model 5" and the trigger is a little better than on the regular M&P but I think the Apex Stuff is even better. JMHO. I have the Hard Sear and USB on my M&P FS and it made a good enough trigger to a great one that is easier to shoot well. I do recommend that you shoot a 1000 rounds or so before changing parts as the trigger does smooth out and get lighter with use.
I have tried many different platforms through the years - Glock, 1911, DA/SA pistols, Revolvers but I really enjoy the M&P's as do the rest of the family.
Good luck, WK