I do not own one but, I have fired them and have range reports from a family member who does own one. So, the particular Sub 2000 we have in our circles needed a common break-in period of about 200 rounds before it would fire whatever we gave it. The ammo that it did have issues with in the beginning was steel cased loads... now however, it shoots everything. I found it to be very reliable and accurate for what it is when I used it and I still have it in the back of my mind to pick one up but, I have other priorities and this weapon wouldn't really fill any specific role. IMO, it is a very useful concept to have a carbine that uses the same pistol mags/caliber, etc and it can absolutely be used for around the house defense, critter getting and even an SHTF weapon for smaller folks. The one in my family is used as a vehicle weapon, a get-home carbine that stays behind the seats of the truck with a few mags ready to go in case of something happening while away from the homestead. Out to 100 meters, this is a potent weapon against unprotected foes and is more so within 50m. It will not however, defeat Level III Kevlar in either caliber... so don't expect any armor-defeating performance with the longer barrel.
Bottom line, if you've got the desire and the cash... get one!