Yeah I was gonna ask - I've used Speedplay frogs. Like them although I now use Time ZControl (I like the bigger platform). Problem with the Frogs is finding a shoe that I didn't have to carve out the bottom so the cleat would fit properly. I think the new Sidi Dominators work OK. I also found I "fell" out of the pedals sometimes, like on a big drop , my foot would disengage from the cleat. But alot of people use them for both road and trail.
I've been using Frogs (Speedplay) for going in 8 years now. I've had shoes I had to carve but the last pair, maybe last two, I haven't had to carve up at all.
They work good in all conditions except I seem to have a little trouble if there's a LOT of sand. It seems to rub the grease off and makes engagement difficult. Keeping them well greased will allow good engagement in the sand.
Otherwise, I love my Frogs. I have them on both my road bike and mtb. I like the complete lack of any spring force for either centering or retention. Some people say it's like standing on an ice cube to pedal, but you get used to it pretty quickly.
I'm currently using the Specialized MTB Comps from a couple of years ago. Nice wide toe box.