It will get a second look when I take it out. But I either keep it in my truck or in a low profile case as much as possible. In fact, when it is in my truck, I keep it in a low profile case. So it isn't obvious at a mere glance. The 'sneaky' bag works extremely well either with the long arm in the open or if keeping it discrete. The 'sneaky' bag gives you the option of being extremely low profile. Although you can make a chest rig lower profile by wearing a over shirt/jacket, it isn't as low profile if somebody is looking you over. Not to mention an overshirt isn't what you want in a hot climate (which is not a consideration for everybody). A messanger bag on a motorcycle looks right at home, as is a saddle bag with a folding stock AK/Shotgun.
I am not saying a chest ring or overt set up is bad. I am just giving the original poster some ideas to think about. I have a chest rig for my rifle that I use at the range and will use if it is an all out hostile situation. But I have found the 'sneaky' bag style set up much more usable in the day to day use. Even in non-emergancy situations, the less people that know I have a firearm the better. That makes for less risk of my truck or house getting broken into.
Also consider the 'legal' issue of overt carry. A chest rig with a drop down thigh holster is good for combat zones or if you are trying to make a show of force. You can do the same by wearing the shotgun/long arm in a sling over your chest with the 'sneaky' bag. But in a situation like Hurricane Katrina where they are actively taking away firearms, the more discrete the better. I am lucky in that were I live (Phoenix, AZ), open carry is 100% legal, so it isn't as big an issue. But in Hawai'i, where I went through both hurricanes, open or 'discrete' carry isn't legal out in the public. You can only go unloaded to or from the range, place of business, residence or hunting. Also keep in mind, most emergancy situations are 'low intensity'. After the hurricane in Hawai'i, I didn't feel the need to be armed all the time, although I kept a gun near by. In fact, the majority of the time I was helping clean up, gather water, rebuilding, etc. You definitely won't want a chest rig when doing those things. The majority of the time, long arms are kept in the truck when you keep a handgun IWB.