I am sorry to hear that you are having problems with unintentional unclipping with your Frogs. I have them on my Gunnar and I really like them, and I've never had a problem like you describe. However, I know that my LBS had them in stock for a quite a long time as I seem to be the only person interested in them for at least several years. The fitter dislikes them so he actively steers people away from them and now they no longer carry them.

I wonder if I have an older version? I can tell when my left foot clips into the pedal - though it is less pronounced than the right foot (I clip in AND out with my right). Once I've clipped in with my left foot I always pull up a bit with the pedal to make certain I've clipped in. I do know that there has been a couple of times when I thought I had clipped in with my left but I either hadn't or it wasn't complete - which is why I do a "test" pull on the pedal to double-check.

I hope that helps a bit - I hear you on not wanting to return to SPD pedals, they just kill the knees, well, mine they do. I also know some women who love Time pedals for mtb use, though I've also heard they can be quite the challenge to work with.