I love that rig. :)
More power to ya. I've trained so much with an 870 from the gunbox ready position that it is what is natural to me. Keep in mind that ours are riding around in vehicles a good bit, and the chance for a jolt or a bump that might set it off are higher. We also have to contend with putting them in and taking them out of vehicles. Prior to putting on the badge I kept mine with a loaded chamber, but I prefer the gunbox ready method. I train that way, and I keep all of my personal shotties that way as well.