I have an M9-A1 and I'm really happy with it. The manual safety in front of the trigger is an option, and it seems that very few of A1's coming into Canada have this option. I haven't seen any A1's in Vancouver with the manual safety. Mine doesn't have the manual safety so I can't really comment much on that. If I were choosing between the two, I would go without the manual safety. Unless you are in a CCW jurisdiction and you were going to carry it, I don't see the point. And even then, if you have a good holster it makes no difference. The safety system on the A1's is the same as on the Glock: trigger, firing pin, and drop - deactivated with each pull of the trigger.
The sites do take some time to get used to, but they work fine and you can get 3 dot sites if the trapazoid is really not your thing.
Felt recoil and muzzle flip are very low, especially on a 9mm. The grip is heavier and sturdier feeling than a Glock. It's a metal frame wrapped in polymer, rather than straight polymer frame.
The barrel takes more work to keep clean than many of its competitors, particularly the hex/poly rifled barrels like Glock and USP. The grooves on the Steyr and deep. Make sure you use some kind of solvent and a jag that'll keep the patches tight, or your accuracy will suffer until you get it clean. Having said that, I find the gun to be very, very accurate. Also, you've got a fully supported chamber, so no worries there.
The best thing about the Steyr in my view is the trigger. It's the shortest, crispest double action trigger I've come across. I love Glocks, but I think the trigger is the weakest part of the Glock system. Steyr is a bit like a Glock with an improved trigger in my view.
I like the look of the gun too. It's not everybody's cup of tea, but I find the thick front end to have a cool "bulldog-ish" look to it. It's more stocky and tough looking than sleak and slender like a High Power or a 1911. The thicker front end is also great for planting your weak-hand thumb if you shoot two handed with your thumbs lined up.
Awesome gun. Highly recommended in 9mm or .40.