Bianchi used to make something called the "scorpio system". It was a very nice shoulder holster that could be taken off the shoulder straps and carried on a belt, mag pouches and all. I don't believe they make it anymore.
As far as the Galco holsters go, I've got one of their Maimi classics and two of their SSII's, I love em. They are great when they are broken in but they are real stiff and tight at first. If you do get the Miami classic or SSII make sure you always pay attention to the tension screw and strap screws, the tension screw will need adjustment as the holster wears in, same for the strap screws.
The Galco stuff is great.