I have been riding with cages or clips across my feet for a few years now.
everyone else in my family has the SPD's, my two adult sons and my husband who thinks a perfect ride is 100 miles long.
But as it has been explained to me, if i convert to the SPD's I WILL fall, and
not being the most coordinated person in the world, I will probably fall a lot.
If falling is an issue for you, that should be a consideration.
I ride a tandem with my husband. he's got those SPD's on his pedals and i have the cages and both times he's done a slow motion dump of the bike, I've landed on my feet and he's gotten scraped elbows.
I probably don't have the things on tight enough, but I am very comfortable with them and at this point, i'm not sure i'm going to change. I'm 54 years old and it hurts to fall down.
I agree with the others, do get the kind of pedals that "go both ways"
everyone i know that has them loves them.
mimi