I tried a set of "J" clips once and did not care for them. If my gun butt got pushed down at all they occasionally got unhooked and simply rode behind my belt. Then when I'd draw the holster would come out with the gun. Nothing but full loops for me.
For clarity, a J-clip goes over the waistband of your pants, then under the bottom of the belt.
The theory behind the J-Clip is that since most of it is behind the belt, they will conceal better. I think it is a pretty good theory for small, light guns. However, for something like a 5" Government model (this is a 1911 forum after all), I think you're asking for the waistband of your pants to provide an awful lot of support for a pretty heavy gun.
I would prefer a standard clip as it would allow the weight of the gun/holster to rest on the belt rather than your pants waistband.