Originally Posted by PeteHski

Exactly, thank you!

Having read a few of those studies, it was interesting to note in one study (Dr Jeff Broker) that not a single one of the 100 elite pros he tested produced positive torque on their upstroke. In fact when pedalling at high cadence and power they were struggling to even overcome gravity acting on their upward moving leg - so they still had a net negative torque on the upstroke. This explains why your feet don't fall off flat pedals on the upstroke.

The edge case of crawling up a steep climb at very low cadence is likely different. I feel like I'm pulling up in that scenario too, but I know I can't produce anything remotely like the same torque as I can on the downstroke - glutes vs hip-flexors is no contest.

All the OP has to realise here is that moving from flat to clipless pedals will not increase his power by allowing him to pull up on his pedals. You can pedal just as smoothly on flat pedals as with clipless. But there are other reasons why clipless pedals are worth trying, which can be either be positive or negative. Foot positioning is far more precise (positive if you are fixed in the optimal position, negative if you are not). There is no risk of slipping off the pedals (if you are prone to that). They allow for a lighter, less bulky pedal (if you care). They make bunny hopping easier (if you do that). They arguably give you more control over bike handling, but I'm not convinced personally having gone back to flats for mountain biking. They give you better security when sprinting flat out.