Wow, I've been following this debate for a while. I posted some of my feelings and observations and even some questions about some of the products mentioned.
I own a 45-70 and would carry that, but I would also carry spray. I would be incline to use the spray first. Here is why...
I have used spray on humans many many times. I used to carry one the size of a small fire extinguisher. These are extremely affective. When you spray a person or for that matter any animal, the animal/person being sprayed is first stunned or surprised. They do not expect to be sprayed, even in the case of a person looking at you with the spray drawn, and do not know what to expect until it is too late. So, it startles them and breaks their focus. In a bear it may only be for a couple seconds, but you just bought precious time. Spray again if needed or draw your gun and fire. I have used spray in not just breeze, but wind. I have been down wind of it and up wind. I will admit that up wind is best, but because the spray is not what people think, it doesn't spray like windex, it sprays like a hard steady stream.
You AK guys correct me if I am wrong, but bear spray is much more powerful and sprays under higher pressure and harder streams then the run of the mill people spray.
Part 2 for me is that when I have shot animals the size of a bear, they were Bison, (More people are killed in Yellowstone by Bison than Bear) the animal was shot and unless the shot is perfect, they stand there and it is a bit before they are sick enough to fall over. A bear may not be scared off by being hit, just like the last two Bison I shot were not scared off by being hit, and I had to shoot them again. The bear probably will not do as a Bison and stand there, they will probably not do like a human that is wounded and try to flee or just fall over in pain, the bear is likely to continue to charge. So, if you do not have spray and only have a gun, you best be pretty damn good in pretty much a lot of panic, fear and ect. Now I say this because while fly fishing a bear decided he wanted my fish more than I did. When he came out of the bush, I was very surprised. I am not sure I want to find out if when I am that scared that I could drop my fishing gear and draw my 45-70 or my .44 and pull the hammer back on the 45-70 or just squeeze of a round of the .44 in time to save myself.
My point in the long response is you can while on the computer typing or at the range be very macho and feel the handgun/rifle/shotgun will make you a bear killer, but from experience when you see a bear coming for you, you will no matter who you are PooP yourself and have the flight instinct kick in! You all can say what you want, but from one who has been there done that, I will never go in the bears domain again without spray and a gun. Spray will be where I can get to it first and it will be used first!
Just my .02. If I am wrong on any point, please correct me, but I don't think I am.
Mel