IMHO, it's a great idea as long as you use foil and cook overnight, or get up really early and keep the temp up. (For an decent rest, I'd try to keep the temp up close to 300* and wrap in foil as soon as the bark looks ok.) Even if cooking over 275, they can be stubborn, and the foil will really help speed up the cook as long as you don't put it off too long.
It's my experience cooking on my 18.5" wsm, that unless wrapping it for part of the cook, it's easy to end up with too much in terms of "burnt ends" if I cook too fast, preferring to cook with water at about 250* at the vent. Protecting the end of the flat with foil and fat trimmings helps, but the flat end is the first part of the brisket to dry out, and it's sitting right over the hottest part of the cooker, afterall.
I cooked briskets in 9-10 hours on my old UDS, no foil, but the temp coming up around SIDES of the drum was mostly sub 250*, with the temp in the middle close to 275 or a little more at the most. I flipped 'em a couple of times as well.