The SPD pedals are easiest with the #56 cleat and not the standard #33 provided. The multi-release cleat allows releasing in three ways: pull-up with toes down, rotate the foot left or right. The pull-up motion (either straight-up or with a foot rotation) is what one does normally (at least I do) when falling over. That allows unclipping with out a conscious decision when falling, yet they hold well enough to do a bunny hop and get the bike off the ground with just the clipping force.

A big advantage of the SPD (#56 or #33) is that the clip-in tension is adjustable. You can adjust them relatively loose until you get get used to them and then increase the tension as you gain confidence. Mine are cranked down pretty tight after some dozen or more years. I don't believe the non-SPDs are adjustable.

It's important to be able to ignore your attachment to the pedals so you can concentrate on the riding. That's particularly true in mountain biking when it gets technical in more dangerous situations. The natural release-ability of the #56 is a big advantage in trail riding. I know some folks with other brands that unclip before the technical/more dangerous parts. Exactly the wrong thing to do as that's where you need your feet attached to the pedals most.

Al