Nice, thorough report. Thanks!
Last time I climbed Shasta, it was in mid-August, and I would never recommend doing it that late in summer. Much more snow had melted, making the climb and descent over loose shoe-box sized rocky terrain pretty miserable. Second reason: that late in the summer, forest fires browned-out the view, so the only thing I could see above the smoke layer was the tip of Mt Lassen to the south.
Did you, or anyone else, glissade on the descent? Shasta is known for being a very nice place to do that.