The Powergrip style requires you to rotate your foot in the strap to "tension" it so to speak, locking ur foot in place. Its sorta like clipping in and out of SPDs.
However, I've seen other types of pedal straps such as the Resistant pedal straps.
Source: http://resistant.exblog.jp/12472150/These straps are different because you dont rotate your foot, but rather tighten with the velcro. Sorta like toeclips. Wonder which design will be more suited for commuting purposes.
There wont be toe protection as with toeclips but with the front wheel clearance on my MTB, that shouldnt be a problem. Just wondering about the safety aspects. I assume with these, I wont grind the pedal straps on the road if I pedal on the non-strap side. Since they are soft, they shouldnt present much of a risk.