Mark
Having seen bear spray applied into the wind and because I have grave concerns for the mechanical aptitude of most folks i think more will get hurt by it than helped. I doubt it is even terribly effective against two-legged predators, a more common concern in my opinion.

I have seen two bears properly and liberally doused with spray. Neither situation was resolved by spray and more effective, and final, means were required.

I have seen a guy spray himself directly in the eyes in his fear. I have seen people "spraying" a bear just walking by... at about 75 yards. I have seen a guy get shot in the small of the back with a half-empty canister that went off in his fanny pack. The blisters extended down the insides of his thighs and included sensitive scrotal tissues!
Firearms or actually using your wits is my thought.
art