Fantastic post thirdeye, I always look forward to your contributions. I've been experimenting with high heat briskets for a bit now, and I am still struggling to get a decent smoke ring. Flavor has been great, but not much of a ring. I've tried all the mentioned tricks, cold meat, low and slow until 140 before ramping up, etc. Still not not much.
I'm not competing, and the flavor is great, so I'm not going to worry too much about it. I might play around with that Tenderquick if my next high heat doesn't produce much of a ring.
The image below was a low heat / high heat combo, I ran at 225-250 until internal temp of brisket was 140, then ramped up to 325 until tender. Brisket was great, but as you can see not much of a smoke ring.