I have never heard of Power Grips, so I can't be of help there.

I also have never tried clipless, and probably won't. (Because I'm a die hard commuter and wear actual people clothes whenever I'm biking... with the exception of a spare t-shirt if it's hot out).

Toe clips and straps are things I wouldn't be able to live without (well, it would feel really weird!). They work for me, even in stop-and-go city traffic (keep the right one always on my foot and flip in and out of the left one as needed).