For road riding and XC mountain biking being clipped in is a must for me. I've ridden flats when I had my mountain bike set up enduro style and we were riding steeps, skinnies and jumps and if you are doing technical trail riding like that I would recommend flats.

But for the most efficiency in your pedaling and the terrain isn't technical like that you can't beat being clipped in imo. Just work on your technique and profit.

And yes, I pull up as well. My goal is to get power in all directions when pedaling. It's not always the case, but it is still the goal.