You will not have the time to turn on any optic for bear defense........I have used a whole host of different red dots, over the years. Inexpensive Bushnell's......mid priced Vortex's, Ultra-dot's & Sig-Sauer's...... to expensive Trijicon's. The one I would recommend is Trijicon. Been using their product's for almost as long as they've been in business. You just can't beat totally automatic operation. No batteries , no rheostats to fiddle with......self compensates for varying light conditions.
I have two of their Accupoint rifle scopes and three of their full size Reflex's. Just yesterday, returned one of the Reflex's back for re-lamping. It was purchased in 1998. Lamp light life is @ ten years. However, they will still operate in all but total darkness, due to the fiber optics. Few months back, I returned a different Reflex, that they could not re-lamp. Trijicon replaced that one, with a brand new one, at no cost. They also returned the un-serviceable unit......that's why I now have three.
Functional for most conditions, just not for total darkness.