@PlastikSchnittstelle - Some American screw terminology for you:
The current renderings have what is commonly referred to as a button head socket screw. This is the type with a low bump profile.
Socket cap screws have the high bump profile.
Flathead, or countersunk, screws sit flush, like the first batch of renderings. These can come in philips, straight slot, socket head (like the first renderings), etc.
Socket screws, socket cap screws, socket head screws, or Allen screws are all different ways to call screws with the hexagon socket. You can mix and match these and people will get the idea.
I'm a little surprised you went with button heads on the latest rendering. I think it goes nicely with the industrial feel but I see the appeal of flat heads. Not a deal breaker for me either way, but I too think flat heads would look the best.
Awesome news on the 75% front!