Recently I've been fishing entirely with barbless flies, and I've pinched down the barbs on everything in my fly boxes. To some extent this is because I'm sure it helps a little bit with survival; the scientific research is mixed on whether this is a big enough difference to matter to whole populations, but I know I used to damage a fish once in a while because the barb made the hook hard to remove, and now I don't. However, my main motive is a form of laziness: I fish places that require barbless hooks sometimes, and it's easier to de-barb everything and err on the side of caution than to keep track of the rules about that.
I found an interesting blog post recently by John Newbury talking about barbless hooks for Czech nymphs
and how retention wasn't very good on barbless hooks that were manufactured using the same designs as barbed hooks but minus the barbs. I assume the same reasoning would apply to pinched barbs, too. As an alternative, he suggested hooks designed for retention when fished barbless such as the Hanak 333 BL and Fulling Mill Czech Hook. I've never used either of those, but the recently-started Montana brand Firehole Sticks
seems to use similar design principles and I have fished those with some success.
However, I haven't really had an opportunity to do a side-by-side comparison between those designed barbless hooks and de-barbed hooks using similar flies. I'm curious if anybody else here has done enough of that to form an opinion.