There is a slightly more comprehensive review of applicable knots:
http://www.needlesports.com/advice/abseilknots.htm

Scan down to comments and note that at least one person claims that the single overhand can slip. I worry about any knot that is only considered 'safe' when you leave long tails. IMO a knot that slips is one that will eventually give up. Which tells me that if you use an overhand you need to double it. Doubled you lose some of its apparent advantages.

I'm also bothered by the emphasis on a knot being easy to untie. It is a useful trait but in a survival situation if a knot welds shut I simply use this high-tech device known as a knife. If you don't simply butcher outside the entire knot you less than a foot of one of the ropes. The ends, where you tying and untying all the time, wear out so trimming back a little is good. Sailors do this sort of trimming as a matter of course. Ropes are expendable and sailor use it without getting romantically involved like climbers seem to.

If you scan down to the Bushwalkers wilderness Rescue Squad the correct link is:
http://www.bwrs.org.au/?q=research

The PDF "Preferred Knots for Use in Canyons" is quite good.

IMHO it backs my opinion that there are several choices that are good. The Fisherman's knot and "Rethreaded
Figure 8", what I know as a Flemish bend slip least are strongest and are otherwise sound. They catch edges more than the double-overhand but in rescue and survival use this is less a concern. Florida is pretty flat and on shorter climbs simply whipping the line slightly clears most snags. Everyone has to make their own choices.