Chazz-- what sig-230 kindly shows, is one of the South African mags installed in his Hi-power
you can see that it protrudes very little. Shamed to say it, but I haven't even fired the SA mags that I bought from CDNN two summers ago. They seem to be of high quality, if anything sturdier than the factory mags. They have a sheet metal follower that is very compact, and this is part of the reason why they can stuff +4. They do rattle a bit when loaded if that matters to you.
FNhipower.com has a forums with info on mags.
I have never heard anyone complain about the function, apart from the fact that they are initially difficult to load to full capacity.