I've had the SMSc for several months and love it. Granted I've not carried it full time yet, and had it out to the range only a few times due to ammo shortage. But so far, even just sitting around the house 'dry firing' I really like it. It's perfectly co-witnessed with the irons and sighted to about 27-30 ft or about 10 yds. So far as I can tell it hasn't changed set point since I put it on. The red dot sits directly on the tip-top of the front iron sight. In other words, if the red dot was my target, my irons would be holding at 6
clock.
As for the aluminum body, I can't imagine it holding up any better than my SMSc (poly) has. That may change when I begin carrying it daily, but I'm thinking with just using reasonable care it will be just fine. If I had to absolutely find something I didn't like about it, it would be the constant 'ON' and no way to turn it off except to remove the battery. That really worried me at first, but now it's just second nature ..... when I pull the gun out the red dot is 'ON'. No biggie! IIRC it was installed around the end of Mar or first of April this year.
On edit: I still have full use of the irons in any event the red dot should go away with this set-up.