Glad to see this post! The breaking power fully loaded with a trailer is great in my opinion. Its when i am at a stop light/sign that i find i need to put more pressure on the pedal then any of my previous trucks. If i don't it tends to creep. it is not a huge thing but i need to be aware to apply more pressure at a stop. I really hope GM can fix this as it would suck to creep into the car in front of me!
I had the same thing happen to me in the summer. Jump did not work. The tow truck driver came and said disconnect the battery for 1 minute. Then reconnected and vroom it started right away. He had seen this happen on a different gmc model the week before. The dealer ship told me next time have it towed in so they can try to figure it out. Pretty sure next time i will do the same thing as i don't typically have time to not drive my truck! Hopefully GM will figure it out so it can be fixed during its next service.