I have 6 cities that I played in this event, and I was surprised by the variation in my luck. I used the same technique on all cities, but the best city ended up with 90 more feathers than my worst city. My lowest city got only 220+, barely getting the 8th evolve. My best city got 310+, getting the portrait and the second base, and ending up in silver. Same technique in all. It came down to which cities won the extra sky essence in the chests.
Just for comparison sake, 4 out of 6 cities got all evolves, with 2 getting only 8. I do not have an ashen phoenix in any city, no stash huts in any, and I didn't spend any diamonds. I saved the 100 essence from the email for the end, but it didn't end up making a difference for any of the cities.