I've got Koolstops on all my bikes, but they're not a panacea. My problem is either (1) getting bike out of garage and rolling it through dewy grass, or (2) rain showers. Either way, it takes a couple of wheel revolutions to dry the rims before the brakes will grab. (Note disk brakes might fix (1) if the grass is shorter than 15", but probably won't do a thing for (2).)
IME the KS shine by not picking up gravel and letting it get embedded in the pads.