Looks like a nice rig really... a lot of folks are fans of a revolver for the use by the guy behind a shield -- there is a tendency for you to "suck up" on the shield and an autoloader can have the back of the slide hit the shield and not pick up a new round... also, clearing a jammed handgun while holding a shield is, well, you can imagine.
So... I know a few people that are strong advocates of a wheel gun in that position -- or other postions where the shooter only has one hand. The failure drill for a wheel gun is after all, to pull the trigger again