"Danger -- controllable even when the griz are around, or mountain lion scat....again more aware and willing to bail at any point... "

My personal feeling is that for a prepared hiker there isn't a great deal of danger in hiking alone. Sure, if a tree falls on me or space aliens attack and only manage to wound me, it could be good to have someone along to help, but I mostly hike on established trails. Generally someone is going to come along at some point. Bears run away from me whether I'm alone or in a group, I've hiked through well known mountain lion areas and have yet to have an encounter. It could happen, but the stats don't suggest that I should worry about it.

Each of us is different here, I can only speak for myself, but I did feel a little --- odd, uncomfortable at first in hiking solo. After doing it for a lot of days in a row, I got pretty comfortable with it. I.e., as the novelty wore off, so did the nervousness. For a fit, intelligent + wise person with some experience who's hiking fairly frequented trails, I don't consider solo hiking to be particularly dangerous.