After riding with the C&V toe clips and straps for years I figured the learning curve for the clipless pedals and shoes would be steep and probably painful. It was the exact opposite for me, having the cleats properly installed and tightened up so as to not allow them to move about, or not disengage, when I was ready to release. Shimano has 3 different float cleats available so getting things sorted isn't hard, and the SPD-SL have a tension adjustment screw on them. My cleats are the 6°,or yellow, float, and I keep the tension at a fairly loose setting. I have no experience with Speedplay or the other systems out so I cannot speak about them.
Also, I never had a clipped pedal accident, but I saw many over the years. Not sure why that happened to those riders with the strap's adjustment available, and most of these didn't have the old style cleat nailed to their shoes. One particular friend was constantly having a clipless style Tombay fall with the toe clips and straps. Truly strange as he was experienced a a cyclist, very coordinated and a collegiate gymnast.
I didn't/don't find either system to be difficult for me. With the problems I now have, from Parkinson's Disease, in my legs, the SPD-SL helps me keep things stable when the twitching starts up mid-ride. An unexpected plus for me.
Bill (Ol' Twitchy)
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Semper Fi, USMC, 1975-1977
I Can Do All Things Through Him, Who Gives Me Strength. Philippians 4:13