You need to read my post again, Smokin.
I am not talking about cooking the briskets at higher temperatures the whole time. Just the first 3 hours. Then I reduce to 225. It takes another 6 - 8 hours to reach the proper internal temp.
In the case of the accidental brisket, it was held at 140, it was not over cooked, just over held. My experience would say that holding at 140 would reak havoc on broccoli, but not on meats... As long as you didnt over cook initially....
While I don't recommend the practice of forgetting briskets for 15 hours at 140, I thought showing you the results after an error would show the advantage of a cookshack!.
To answer your question, I think that other holding methods other than the cookshack would have been less desirable.
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"it's done when it's been held for 15 hours!"