Just make sure to look at the actual M9 you're buying if you're particular about having the correct roll marks . Seems to be there has been variations in the roll marking of the slides recently including having Gallatin, TN in the roll marks which they never had before and not correct. The very early M9s were made in Italy until they got the US production up and running.
I bought this M9 in Aug 2019 and has the correct roll marks. The slide above is from an actual Italian made M9
I saw this one at the samel shop in January 2020. "US 9MM M9" shouldn't be on this side and the cage code 65490 should be after the assy number. The roll marks don't look as clean as before.
And this side of the slide looks like standard 92FS roll mark. Note the serial number has a CA suffix. Not really sure if that was intentional for the Calif. roster.
As for the M9A1, I bought this in Jan 2019. Only thing I noticed is the frame anodizing is a lighter shade of black, the barrel machining is horrible and there was a nick on one corner of my light rail.