Yep, having gone from Time ATAC / SBC shoes I have found that Shimano MX30 and TNF Hedgehog shoes are a winning combo with extralong pins. Forget weight, "efficiency" and other crap. Fit, comfort and ability to walk/push/drink beer are ALL more important!
I know there's the power difference, but aside from that I just don't feel confident on flats. Just bought a new singlespeed that came with flatties - decent-ish Wellgo ones - and didn't have a chance to switch them before the first ride. All the way round the loop I just felt rubbish with them: less confident on rough sections, couldn't get a good solid-feeling foot position, couldn't lift the back end on jumpy bits, couldn't steer the back round on tight corners, and worst of all, slipped a pedal and took a whacking great gash out of my shin. Okay, some of the above may be my riding ability (or lack of), some may just be confidence, but I've found very little in the UK that I'm not happy clipped in on. The extra power input is just a bonus on top of that, I reckon.
"Where you've been is good and gone, all you keep's the getting there..."
Flat pedals for me . . . DMR Vault's on my 69er and single speed with Five Ten Karver's. Very grippy and probably safer for me with the amount of times I fall off!
V12's for me and I ride with a pair of five tens impact lows they are super grippy, occassioanly I wear a pair of five ten camp4's-same again super grippy