I think bear spray is a waste of money, weight, and adds a false sense of security. If you are careful about your food and considerate towards animals - while in their home - then you will be fine most of the time.

As a guide, my boss always made us carry spray but it was more to ease the mental anguish of the parents of the teens that were going with us, than to actually fight off a bear. In over 10 years, he said he never even tested it. (That seems silly now.)

Wind is a good consideration. Another idea - you have to actually have the spray can on your person 24/7 for you to be able to use it. To the privy, to get water... everywhere. I'm not always with my pack right there beside me.