Here are some sites with tests of the Overhand Bend (EDK) and some alternatives:
Tom Moyer
http://user.xmission.com/~tmoyer/testing/EDK.html prefers a Figure 8 follow-through with safeties.
This site
http://www.needlesports.com/catalogu...9-9c9e00a60c7f has some tests on the EDK (which they call simply Overhand) and the EDK with a backup Overhand Bend (which they call a Double Overhand).
This site
http://www.gudelius.de/spst.htm has a couple of interesting alternatives, tested by Edelrid. The one he calls the Triple T-Fisherman's Knot looks especially easy to tie.
All agree that the Flat Figure 8 is dangerous and should never be used.