That brisket has pretty nice marbling.
I cook all my briskets hot and fast, albeit a different "fuel choice". 300 degrees straight through the entire cook. I usually start with a 14-15lb brisket and trim down to 9-11 lbs. I remove all white fat that I can get to and separate the flat and point down to where it is connected by an inch or two. I leave most of the fat cap in place.
Total cook time is 5.5 - 7 hours. Wagyu's take closer to 6-7 hours. The primes are usually between 5.5-6.5 hours. That is also in foil for at least half of that cook.
I'm surprised that it was jello after 5.5 hours, especially given that it was at 180 for the first hour, 275 the last two hours, and I presume you never wrapped.
When my brisket is over, its still super moist. I just can't slice it like I normally do. Also, it's important to realize that when cooking hot and fast, if you go until probe tender, you will find that the internal temp of the brisket is much higher than it would be if you cooked it low and slow.