I had a Storm carbine that I regret selling that used the same mags, mags that are hell for stout. I ran over one with a Jeep and it still worked.
Presume the A1 gets you the light rail on the dust shield?
Also astounded at the 'plastic' parts that you can replace; my older one came with steel trigger and mag release.
What are they putting in the mil spec guns?
For a double stack pistol, the M9 gets good grades for not being too bulky in the grip.
Enjoy your pistol.
One caveat; the first one I had had an oversize bore and was putting the bullets thru' the target sideways.
The current one has no such issues.