I know they look cool and I'd go for them too but... look where the window is. Our mags would always look empty even when full at 5 rounds. Unless they make 50 Beuwolf mags then there isn't really any point for us.
On a side note the HERA lowers I have are fantastic. Very high quality and well thought out. They even include a quality SS hex nut screw for the pistol grip. I would suspect the mag design and quality would be good. The only concern I would have is the follower, tilt issues and how does it work in non AR rifle systems? The last one has been a major concern for me and the reason I've never bought Pmags. The Pmag is now at gen3 to get things right.