Hi @FlavourFade
I saw a discussion on this earlier in this thread so I was wondering myself too. I have gotten mine only a few days ago and haven't gotten them hemmed yet so I am just wearing around the house. I do find the duck less breathable compare to my 555 21oz. Having said that, my 21oz are almost two years old and have stretched to a point that they are a little loose so this may impact breathability too.
I will report back after a few months.