I'm riding clipless on a hybrid. I think it depends on your riding style. As others have said, if you like to stand and mash and really beat it up hills, you'll benefit from clipless.
Personally, when I hit a hill I just downshift and spin faster. I haven't stood up out of the saddle in years. I'm not racing, I'm just going to work and back. I don't really care if I'm clipless or not. Clipless is kind of nice, but I don't consider it essential.
I did discover one clipless benefit this morning. It was 5*F, and when I got to work the power was out so I turned around and rode home. My toes were getting really cold, and it helped to warm them up by pulling upwards, forwards, backwards, etc to try to increase the circulation in my toes.
Actually after this morning, I'm seriously thinking about ordering up some powergrips and starting to wear my insulated waffle stompers when it gets < 20*F.
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Work: the 8 hours that separates bike rides.