I tried clipless and had to go back to toeclips because I couldn't get my persnickety left knee into a comfortable position with the clipless pedal, even though I used the ones with the most float--Speedplay Frogs. My LBS worked with me, and adjusted the cleat several times, but to no avail--I just couldn't make my knee happy.

Having said that, though, I would LOVE to be able to use clipless. Just the short time I did use them was enough to prove to me that, if you can get the right ones for you, they are actually safer than toeclips. I mean, if you really tighten down the strap on a toeclip, it's harder to get out of than a clipless pedal, at least the Frogs. If you decide to try clipless, get them from an LBS you trust, where they'll put your bike on a trainer and let you check positioning of the cleats and practice clipping in and out a few times. Sure you might be able to get a better price online (or you might not), but the online store won't be there when you need help with installment and adjustment.

I've recently been reading that the new Frogs have even MORE float than the old ones, so I might give them a try again.