its their long fit, so XL is the exact same size as XL saga but with shorter sleeves, which IMO makes it a nicer fit cause you don't have such huge flappy sleeves. The fit should be perfect for you if your 6', I have a large armory from last year and I'm 6' (same fit) and I could easily go an inch bigger to the xl size.
I am 5'9" and I wear a XXL and I personally think the fit is perfect. I'd get XXL if I were you, no question. Also, contrary to what homie said up there, I found that I could literally wear a T-shirt, hoodie, then tall-T every day and was never too hot or too cold.