All good responses. Thanks to Dagny for the ladies' perspective. Here in the SouthEast we've had a few lone women attacked on trails.
The whole "solo or no?" question has to be rooted in what you want to get out of the experience. If the sole issue is safety, then never go in the woods at all. Beyond that, know the risks, know thyself, and reap the rewards of prudent adventuring.
One big thing I'd say to my fellow solists is this: be MORE willing to back off than you would if you had partners. IMO the threshold for bailing on "the plan" has to be lower for the soloist.
I imagine hiking alone is a lot safer than driving down the average freeway. It's just that hiking, since it's in a "wild" place is a associated with danger.
Word! Years ago I rope-soloed a challenging 2 day big wall climb. It went off without a hitch (get it...?). The closest I came to dying was on the drive home when a guy ran a stopsign and almost crashed into me.