Is this a place to use that common phrase, :it's better to have them and not need them than to need them and not have them?"
But the thread reminds me of some photos in the news a year or two ago (time flies) of some civil disturbance somewhere in South East Asia. Most of the people in the photo, including a lot of the uniformed soldiers were wearing flip-flops, so none of them considered it a handicap. However, there was a photo of an empty street after it had been cleared and there were a couple dozen flip-flops lying on the pavement.
Sandals are almost a world apart from flip-flops. I once experimented with wearing plain velcro'd sandals on a trail in the woods, the Appalachian Trail as a matter of fact. They worked pretty well and one seems to automatically compensate for the differences when walking. The idea was for something to wear when it was wet, though I repeated the experience.
By the way, on the subject of walking in the woods, if you do a lot of long distance walking and it rains, you get wet eventually, although I've had pretty good success with an ordinary poncho. Eventually, everything gets soaked if it isn't wrapped in something waterproof. Something to think about if you carry a handgun but it really only becomes a problem after an extended period. Besides, if you don't wash so often, you become fairly waterproof anyway, only that doesn't apply to blue steel.
As far as running in sandals goes, well, I'm pretty much beyond the age of doing much running even though ten miles on a mountain trail still amounts to an easy morning's tramp.