My personal opinion is that if a predator really wants to get in they will. You can and should do all things possible to make it as tough as you can on them, but a determined coon, skunk, possum, or especially coyote or neighborhood dog will get what they want. I think dogs are the most dangerous to a flock because they have no fear of humans so scent, motion, and many other things that will at least temporarily deter a wild animal won't even phase a dog. My expectations are that my coop and run will at least take a predator some time to break into...hopefully a night or two so I will have time to see something has been trying and then I can set a trap or wait for them and take care of them. Most nights my birds are locked up tight in the coop, but my run is covered and has wire buried and running 24 inches out so if we get back late or are out of town it should be ok for the door to be left open.....I just don't do it often so as to tempt anything. The set-up you have sounds secure (assuming the run is covered) but keep a close eye for spots where something has been digging or trying to break in and repair or re-enforce as needed and you should be good.
Chris