[commando552]

My only real experience with concealed carry was with a vertical shoulder holster. For what I was using it for it worked perfectly well, mainly because I had to conceal a full size Browning Hi Power, and not being able to take my jacket (or an outer shirt depending on the weather) off wasn't really an issue as that concealed a whole bunch of other stuff like magazines, vest, radio, etc. I will say though that I did spend pretty much a solid day adjusting the thing to get it to the point where it was just right for me which is obviously not so much of an issue with a waist holster. I have tried IWB holsters, and to me they always seemed a hell of a lot less comfortable and harder to ignore than that shoulder holster, but this might just be that I would have to get used to them.

With your back injury, can you comfortably draw quickly from a normal strong side IWB position? Assuming you are carrying at around the 4 o'clock you will most likely have to twist your back slightly to get your hand to the grip, and particularly in a self defence situation I can imagine overdoing it to get the hand back to their gun and screwing your back up. At one point I had a herniated disc (luckily it was minor and pretty much fully healed without intervention in about 5 or 6 months), and while that was still giving me problems this was the case for me.

A shoulder holster (along with cross draw or appendix holsters) would have the advantage that you are just reaching across the front of your body without having to twist. A disadvantage though, I don't think a lot of ranges or classes will let you use a shoulder holster due to the fact that the muzzle will most likely (definitely in the case of a horizontal holster) be pointing behind you at some point during the draw. This means that it could be harder to practice live firing with it.

Another advantage of a shoulder holster if you are going for something like a Galco Miami Classic, is that it has built in magazine holders. This has a few advantage, first being that it balances up the holster making it more comfortable. Secondly, it is one less thing you have to find room for on your belt or in your pockets, along with the fact that it is a lot quicker to put on. A shoulder holster also has the advantage that there is no messing about with having to have the write trousers on or belt and you don't need to thread anything or do anything up (with the huge caveat though that you have to wear something over the top though).