Why not throw these two expressions around? You may suddenly find yourself becoming the smoothest guy or gal in the commune or the yoga studio. The only problem is that I'm not sure how anyone can say either of these things while keeping a straight face. Is anyone really this cool or this relaxed? I can verify for a fact that the large number of people that I run into casually dropping "No worries", which is nearly interchangeable with "It's all good," are definitely not that cool and probably not all that relaxed either.
Some people can pull it off slightly better than others. The other day I heard a yoga instructor hand out "No worries" in the middle of a vinyasa, which I was almost able to let slide by me without the hairs on my pet-peeve-o-meter standing up, but stand up they did. Once I was in a grocery store in Breckenridge when a tourist toppled a small display of crackers. A middle aged woman actually responded to the situation by informing the shopper that "this is Breckenridge, No worries." So perhaps it is the place, and not the person, that sets the level of coolness and relaxation equal to the awesomeness of the expression. Although this is up for debate, as the mall and/or your local Applebees seem to be perfectly acceptable terrain in which to utter "It's all good, bro."
However, there could be some truth to this idea of place. It turns out that "No Worries" is actually a valid saying that originated in Australia and has apparently been used there for many years before invading the mouths of yogis, pseudo-hippies, middle aged Breckenridge-ites, and millions of other Americans. "It's all good, mate" rolling off the tongue of the Man from Snowy River just might work.