I have always used UDAP, they were one of the first to market with a dedicated big can of spray for bears. I know they have done a bunch of testing and are very active in the regulations around sprays. The founder of the company was scratched, so he has a pretty solid viewpoint of what goes down.
When my current can expires, I'm going to probably buy the bigger one. I use expired cans for practice, just be very careful of the wind and wear goggles. It was a big help to me to see what it actually does and get a solid view of the range and spread. I believe they make inert cans for that purpose which would be an even better idea.
