What did you use previously? I think you will find different pedals feel different for the same cleat type.

I just don't understand the issue you are having. To me it sounds as if you don't have enough strength in your ankles to overcome the power you legs are putting into the pedals. And I guess that's okay, you probably do need to find a cleat and pedal combination that works for you.

SPD's are considered easier to click out of, I think... so maybe they can be more prone to foot wobble or whatever you say your trouble is. I just have not noticed myself.