Picking this up because I recently developed a strange muscle pain in the backs of my legs. After talking to a friend of mine who is a colligate cycling coach, he indicated that 15 years of riding clipped in may have taken its toll on my pedaling technique. His recommendation was switch to flats.
The first thing I did was start looking into shoes - I knew my "barefoot" or "minimalist" or whatever you want to call them every day shoes (Merrell Trail Gloves, for the record) wouldn't cut it for mashing on pedals, and research seemed to indicate 5.10 was the way to go. I picked up a pair of Spitfires off Amazon directly from 5.10 for $49 - apparently they're 2012's but my feet don't seem to care.
I looked into pedals, and there were a lot of recommendations out there. A common theme I ran across was this is good, and replaceable pins or spikes is even better. Since I have a set of Xpedo Mountain Force (4?) clipless pedals I've been very impressed with (lighter than XT's, half the price, more durable) I figured I'd see if they had anything to offer that fit the theme of what other people are recommending - and they do, the $79 Spry, 11mm thick and 260g.
The Xpedo's will be going on the bike as soon as they get here, meanwhile, the 5.10's arrived, and I threw a set of cheap (honestly don't know what these things are) alloy flats on that I had bought for my son's old bike when he wore out the stock pedals. They weren't being used because he out grew that bike, and his sister hasn't grown into it yet.
First ride on flats yesterday in 15 years or so, and I managed fairly well. I still remember how to bunny hop without cheating, and was even able to take a small jump without coming off the pedals. I was for sure slower on some climbs, but on the whole, I had every bit as much fun on flats as I did clipless.