Just bought two sets of the Power Grip Pedals for our Rovers, mine and my wife's. Not sure why I got the wife a set as she never rides her Rover!
The pedals went on in a snap and the straps were perfectly adjusted for my shoe size right out of the box. As I pulled out of the garage and started up my fairly steep driveway to the street I instantly realized the strap was helping with the pedal effort in a climb. My foot feels more secure on the pedals as I ride and by just pointing my toes inward (pigeon toed) they are easy to slide out of. Took a nice ride today and I am very pleased with this simple add on feature very comfortable to use. The main reason I wanted these pedals was to guard against possible foot suck. I would suppose your foot could still slip out and fall down, but it seems that it adds security from your foot bouncing off from say a bump or jar. Now if I could just get my wife to spend some time on hers, oh well, just saying.