It's hard to give a percentage because most people who make the transition to toeclips or clipless are relative beginners whose fitness are still improving. I would go straight to clipless. They let you pull back on the pedals. Toeclips do not, unless you use cleats; but then you would need to reach down to loosen the straps before you stop. Additionally, I don't even know where you can buy quill pedal cycling shoes these days.
Sorry, this is just plain wrong. Whether you have to loosen your straps before you stop depends on how tight you set them. There's no requirement with toe clips to tighten yourself in. People who promote this have generally not lived with them.
Road Fan