The DX plastic cage pedal is what you want. Not very expensive, zero maintenance, does the job. This is after trying various styles of pedal over the years. They are simply one of those "no brainer" parts.
I do think the cage is fairly useless on clipless pedals though. If anything it provides the mechanism with more rock protection and that is about it.
Sorry Tim, this is incorrect.
Primarily, the cage provides a larger surface area to spread the impacts that DH inflicts on your feet. Try flat landing a 10m jump, or doing a day at Thredbo, with XC pedals fitted to your DH bike, and you will get the idea...
The cage is also handy if you get unclipped and can't get back in right away, you can ride it like a flat pedal if you have rubber soled shoes like DX66S or Minnars.