Great Shoulder Rigs
I have worn shoulder holsters now for about 20 years. My usual carry was a Colt Commander, but these last 8 or so years I've been carrying either a Sign P220 SAS or a Sig P229. I have rigs made up for each.
Overall I have found the shoulder rigs to be comfortable, easy to wear, very concealable, and adaptable. For some time I wore the Commander under a survival vest in the airplane I was flying (flight surgeon). It was comfortable there and I felt great peace of mind with a .45 and not the service .38. These days I still carry .45 ACP, but will also carry the P229 in .357 Sig. Weapon plus several mags is a lot of weight to hang on a belt; this is a far simpler way to carry an effective load without discomfort or loss of concealability.