I agree with the post above, if you like the feel of clipless pedals then stick with them but if not, then stick with flats. I wouldn't worry about efficiency as the boost for clipless is small and the 'pull up boost' doesn't actually happen*
I was badgered relentlessly for a while to change to clipless pedals being told about how much faster and further I could go and do all day cycling. I gave in and changed to clipless pedals but never liked the feel of them even after a lot of adjustment. Still I was told how much better they were and to stick with it so I changed to another clipless pedal system, didn't get on well with them either so eventually gave in and switched back to flats. I wish I'd done it sooner, much prefer the feel of the flats and I've had no problem with century rides, endurance racing, CX races and all day riding. With a good set of shoes/pedals there's no issues with pedal slips even on rough terrain.
I appreciate that many people like the feel of clipless and will be better when riding them but I dislike this mythical status they've now got where the benefits are so massively overstated that people now will genuinely claim it isn't possible to do certain tasks without clipless pedals. I was doing a race on a hefty bike (15kg+) against super lightweight carbon fibre bikes that probably weighed less than my wheelset. I got second in class and even managed to lap some of the bikes (in local club colours) yet it wasn't the fact that I did so on a much heavier bike that surprised people...it was the fact I did it with flat pedals because it's not possible to do that without clipless.
I still get regularly told how I should switch to clipless and I'll appreciate the benefits when I start to do longer rides, people are genuinely surprised when I tell them I have no issue doing longer rides on my flats and a good bit faster than when I rode clipless. Not because flat pedals are more efficient but because I prefer the feel of them, same reason why people think their clipless set up is much faster.
*
https://roadcyclinguk.com/riding/bike-fitting-the-myth-of-the-upstroke.html