I have a Steyr M-9. It is identical to the M-40 except for magazine and barrel.
There are two generations of each, the original the updated "A1" version. CDNN is currently selling fairly inexpensively the current A1 version. Mine is the first generation. Major differences some minor appearance items, type of accessory rail, and only first generation had the manual safety; A1 is basically like a Glock with only a trigger "safety." That extra safety on the first gen was one of its most significant distinguishing features, and it's a shame they got rid of it.
I am pretty happy with my M9. It is well made, comfortable to shoot, and has been fairly reliable. Trigger pull feels like a stiff single action, although the mechanism is actually about the same as what's in a Glock. However, when it gets moderately dirty, after only 100 rounds or so, the ejection pattern changes from sending brass to the right, to sending brass straight back. Brass often hits me in the forehead or glasses! I find this a major nuisance as 100rds is not a huge range session in my view. I also consider it a potential liability for self-defense. If it's clean the ejection is fine, and it's highly unlikely you would fire 100rds in a self-defense scenario (unless it involves zombies), but just FYI.
Interesting history on the Steyr - supposedly it was designed by an Austrian policeman who had a Glock as his issue sidearm and wanted to correct everything he thought was wrong with it. He offered his changes to Glock and, surprise, they didn't take him up! But then he went to Steyr and apparently they were more receptive.
One other note - the Steyr M-series was originally designed around the .40S&W, and the 9mm is an adapted version. That means the feed geometry is better for the fatter .40 and .357 Sig cases and therefore allows full case support, while it should be fully reliable.