Ventilation is...fair... Holes in the padding, but nothing like an external frame, but I can live with it.
I had cranked down on the straps for the bypass harness, so I remember it was pulled unusually close to my "noggin". Was not necessary to do so for comfort. As Jedi5150 stated, I can bend the upper part of the stays back, but have never needed too.
Dan's bypass harness is truly the "cat's meow". Once I tried it, I will NEVER EVER go back to load lifters.
