Since this has already been bumped by somebody else, I'll reply to this:
Ray
Maybe if you've got regular old road cycling clips, but if you've got something specifically designed for MTBing (e.g. SPD's), clip-less is much, much safer than toe clips. They hold tighter, when I want them to, and I'm in and out of my clip-less much faster than toe clips. Plus, I'm a lot more stable and can use more "body english" on a descent.Clipless and mountain bikes... Ok for road riding (I used to be huge into both mountain biking and road riding), but I'd avoid them for rough terrain. Too risky.
Ray