I didn't see the extra vents in the pictures, just the one above the nest boxes. Do you have any pictures of the coop, showing the other vents? Having another vent added up high on both ends, as you describe, could help a lot with ventilation, depending on the sizes.
When you mentioned double doors on the side as a vent, do you mean the service doors on the side? That would work great during the day to cool it off or vent more moisture, but not at all when they're cooped up at night or in the morning. Sometimes people need to have their chickens locked in the coop temporarily during the day for various reasons, too. So, I think the other ventilation openings are extremely important. Many people also build the run coming right off the pop door, instead of having the entire coop inside the run. In that case, the open service doors would let the chickens out. These are just considerations for anyone wanting to go with this design.
It looks like it's sturdy, which is a big plus, compared to a lot of the little prefab coops.
Spacing issues, well, that's pretty much a problem with every coop and plan being sold.