I wasn't that impressed with the Power Grips, also tried SPD and am back on platforms. However I have been looking at some of the new types of straps on the market. Some go as a band straight across the pedal some on a diagonal like the Powergrip. But they all adjust via velcro so very easy to change if wearing different shoes. This was a problem for me with the Powergrips as I'll ride in anything from chunky boots to trainers. There's even instructions online to make your own velcro straps. But I don't feel any burning imperative to be attached to the pedals.
I strongly disagree with the idea around SPD/clipless being a light and day difference. Decent platforms and grippy soles will stop your feet slipping. On a steep hill I believe clipless will allow for some pull up in the stroke. For me the benefits don't outweigh the negatives of falling off, having to have special shoes and being unable to reposition your foot at will.