Cleat Clearance
I had that problem - but putting the plastic spacer in sorted it for me. It seemed to need the extra 'height' for the cleat to fit snugly into the mechanism.
They're a tops pedal.
Yeah, that wasn't a problem with my Sidis. There was a perfect amount of clearance for the spring to close on the cleat.
I bought my 3ti's new, so there certainly weren't any wear issues. My mates shoes with Mallets on his BMX felt exactly the same; super vague and far too easy to accidentally release. The cleat is working against the spring as soon as you move your foot left or right and it’s just the lip on the cleat that changes the release angle. You feel a little resistance and then pop! They open and you’re out while climbing that nasty hill. It was always on my mind while riding and slowed me down. To be honest, they actually started to work a little better once the edges wore off the cleats. This allowed the wings to stay closed over a wider angle range, but this still wasn’t good enough. Maybe I should have tried filing them down a little.
In the end, I was left scratching my head. They're probably a great pedal for a beginner. There's no way you'd get stuck clipped in. But for me, they just didn’t work.
Time pedals carry a slight weight penalty over the eggbeaters, but the spring mechanism is far more secure. I have never once popped out of them accidentally! They’re probably not the best pedal to use after buying that first serious MTB, but if you like to be attached to your bike and only pop out when required; I feel they’re the best pedal design in the world.