My coop pophole is situated facing towards a corner of the run, which is covered with tarpaulin so winds don't blow directly inside. The Green Frog door is basically an isosceles triangle suspended by its narrowest point, adjustable so you can set it to be fully open in summer and a bit narrower in winter. This is a benefit but not absolutely necessary, the normal rectangular door would be just as good. So long as the birds aren't exposed to wind and rain blowing in directly though the pophole, they're fine with an open door and as you say the ventilation is good. Chickens are very well insulated in their fitted 'duvets' and really don't need to be kept warm if they're in a dry coop. In fact, as much air as possible and the ability to get up very early is a real benefit to them, especially in the hot summer nights. I've always done it this way, and in all the years I've kept hens I've never had any respiratory infections in any of them.
Also, it's much easier when we go away, to find someone who will check and feed etc once a day, without having to keep on popping round morning and evening as well.
I hope to get my chickens the first week of June.
