Glad to hear you're recovered and doing well. Keep it that way.
M&P versus Glock?
Who cares? Pick either or both.
I've handled and shot Glocks off & on since the late 80's. Experienced and observed minor malfunctions and problems requiring need for replacement parts. No big deal. That's why I became a Glock armorer, after all.
I also went through the M&P armorer class, but I never heard about about a specific problem or recommendation involving replacement of the standard trigger spring in the event of submersion. Never heard of the need to replace many of the smaller springs in the traditional pistols if they were submerged, either, as long as they were stripped and cleaned reasonably quickly.
I did have to replace some small springs in a 4006 that another agency brought me one time ... more than a year after it had been submerged in salt water (without examination or cleaning by an armorer).
The M&P trigger spring is like the one used in the Sigma in that it has a fiber insert installed to help dampen recoil vibrations, to help prevent metal fatigue and breakage caused by recoil forces (harmonics). I'd be more concerned to check to make sure the insert hadn't slipped free of the spring when it became soaked/sodden after a submersion, and then make sure it was completely dried out. (Although it would be easy enough to just replace the assembly and not worry about whether the insert was completely dried -maybe that's where the recommendation came from via the other armorer/armorer class.)
In an early Sigma armorer class I was once told that if a fiber insert were to become soaked and slip free of the trigger spring that the pistol would probably function fine for upwards of perhaps 3,000 rounds before the spring might fatigue and break. I was also told that a 'field repair' could be done using a rolled and compressed bit of material from a cigarette filter until a fiber insert could be obtained.
I only own a couple of Glocks. I really only bought them because I went through the Glock armorer class and thought I probably ought to own at least one of them.
The grip angle, dimensions and overall ergonomics aren't my personal favorite, although I adapted to them easily enough. They're a decent pistol. Good quality. Fine for their intended use. They've had, and will probably continue to have, revisions, upgrades, refinements and improvements.
I happen to think the Glock design is at its best in the 9mm model line, but that's just a personal opinion.
I bought a M&P pistol for much the same reason ... because I took the armorer class.
Ergonomics are much more akin to what I've become accustomed to over the years of owning and using 1911's. Pretty decent.
The trigger is better than the Sigma (to my thinking) ... and you've always like the Sigma anyway, haven't you?
Reliability has seemed to be very good.
Accuracy is much better than I'd expected, especially with the heavier trigger in the M&P .45 model. Surprisingly so.
The guys on the project design team did manage to come up with some arguable improvements when it comes to some of the features of the M&P.
While I won't be getting rid of my couple of Glocks ... I doubt I'll buy any more of them.
However, I might pick up another M&P pistol. If so, it will probably be a compact .40 S&W model, at which time I'll permanently retire my G27 to the back of the safe ... alongside the 4040PD I want to keep but don't feel inclined to carry.
Unless I decide I have a use for a M&P Pro-Series, sometime ... even though I have little interest in becoming involved with 'sporting' pursuits after I retire (IDPA, etc.).
Depends. Dunno.
If you're that heavily invested in the Glock platform, and it serves your needs well enough, why dabble elsewhere? Unless, of course, you're like me and sometimes decide to relent when it comes to trying this, that and the other ...
Fortunately for me, I've had no interest in spending my money on some platforms and designs. For example, while they're fine products and I've had some experience with them, I've had absolutely no interest in buying any HK's or XD's. Heck, I even turned down the opportunity to buy what I was told was an unfired Beretta 92 being sold by another agency ... for $216, I think was the quoted price. Not worth it ... to me.
I turned down the chance to buy the just-then-being-imported G20, or a G19/22/23, for an individual LE price of $311 w/3 magazines back in 1990, too. Looking back at it, the G20 might've been a decent purchase for a 10mm range gun. Oh well.
Stay well, okay?