I have not had much luck with waxed cotton. The filson stuff is hot and sweaty. But their hats and their chaps. But the chaps will turn briars and any very light dew but not for long.
I invested in a very expensive Orvis hunting coat that was waxed. Besides being ridiculously heavy it was stiff in the cold and hot in mild temps. Worst of all, water vapor condensed on the inside and left me dripping wet in a day's worth of pheasant hunting. It was okay for around town but not much else. The Barbour products must be much different to generate all the appeal. But I stick with unwaxed cotton until conditions warrant switching to synthetics. There is a plethora of really improved clothes and boots, especially, that have been created by the hunting industry in the last 15-20 yrs that really are superior in my opinion. Some of it is even noncamo.