Mhumm38,
I'm up to 11 cooks with my 008. No a lot, but I'm learning and having fun. I've never had a bad outcome. The major issue is the one you are having -- how long will this take?
The first two times I tried Brisket, the results were good, but I knew I could do better. I used flats of 5.6lb and 3.8 lb at 225 shooting for 190 internal. It took about 2 hrs per pound to hit that number in both cases. The results wer e a little too dry for my liking.
Using my male brain, that told me that size matters, I decided to experiment with the largest size brisket I could find, which was only 7.7 lbs. 225 shooting for 190 internal. I hit this number in 9.5 hours, rather than the 14-15 I expected from past experience.
The results were the best brisket I have done. Way more juicy and in less time per pound than before. Not sure what is going on with this one.
I have a lot of theories, but my latest one that seems to make the most sense is that maybe the same internal temperature doesn't get you too the same level of doneness for different sizes of brisket. I think SmokinOkie kind of indicates this in Brisket 101. He says that he shoots for lower temps in smaller briskets, if I remember correctly. So, in this case, I should have shot for lower internals with my smaller cuts and had more juicy results (and lower time per lb).
My other theory is that with brisket, maybe bigger is just better. The brisket is often in the same fooprint, just thicker. Thicker means more meat to hold in juices, etc.
I'm also guessing that meat shape has a lot to do with time/lb. 7 lbs in a flat probably would cook faster than 7 lbs in a ball, like shoulder. Also for a flat, as weight goes up, the thickness doesn't increase as much as a round object, so there maybe some kind of non-linear dynamics that straight time/lb rules of thumb won't work for.
Luckily, nothing I have done has been bad, so experimenting always leads to enjoyable product. Ultimately, we probably all have to develop our own approaches based on our experiences.