I haven't played with bear popper's they sound cool. Like pocket flares though, I'd be afraid of starting the woods on fire.
I do frequent black bear country and I've laid out a four tier system for black bear encounters in camp that I'll share.
Scenario: A bear comes into camp being a general pain the the @$$.
T-1. Me yelling and screaming looking all big and pissed./If bear stays and gets all big and pissed, see two.
T-2. Start blasting the small marine air horn, LOUD is a under statement for these things./Bear starts dancing to the sound of the air horn and decides to stay, see three.
T-3. Bear spray, this is third because you can't always pick if you and your gear are down wind or not./

please be gone, if not see four.
T-4. Not as straight forward as the rest but has to do with a quick prayer, knife, hatchet, and frying pan./Assuming I live through tier four I'll be hungry.
Every tier has been proven reliable by people over the years so I'm comfortable with the plan, until tier four that is.:foot:
I can't stress enough the importance of keeping a clean camp. I'm personally a bit over the top with camp cleanliness, I haven't had an encounter while in camp though either. I'll also keep moving if I find a site that has food scraps and trash spread about.:grumpy: Always look before you unload.
I don't worry about bear encounters on portage trails. I have a 17.5 foot canoe over my head and a big pack on so my eyes are only looking at where my feet are going. I suppose one could walk in front of me, that'd be interesting.
I love guns too, but I find myself on the wrong side of the border from time to time while canoeing and don't want to spend anymore time in Canada then I have to.
I know your backpacking but you may find some of it useful.
Have fun and stay safe.