I've been carrying a SW99 .40 S&W as one of my issued weapons for the last few years, although I carry currently 165gr RA40TA ammunition (issued).
I remember when I was waiting to be issued one ...
I had just bought one of my own after going through my first SW99/P99 armorer's class, and I was approved to take it to a week long training class which included a fair amount of range time. I ran most of a case (450-ish) of 180gr ammunition through it without any problems ... which is more than I can say for a couple of cops from another agency who were carrying issued Glock .40's. One of the other guys from my agency attending it with me had already received his issued SW99 .40 S&W, and his pistol also functioned without problems ... as did the issued TDA S&W 9mm another of our guys carried, FWIW.
I took the expected amount of good-natured teasing by some of the other cops for carrying a S&W, of course. The interesting thing is that at one point one of the instructors overheard some of the ribbing, and casually made it a point to mention that in all his years of training other cops, and seeing all of the various handguns come through his classes, the one thing he could say about S&W pistols is that they had always functioned when observed in his classes. He didn't carry a S&W, BTW ...
The location of the decocking button is awkward for many folks, granted.
Naturally, there are numerous training & equipment issues to be considered in learning to use any issued handgun, including the design and model(s) of duty holster issued/approved, but that's for your friend's new agency to address.