I've got four butts on my UDS right now. Each one weighed about 8lbs. At that weight, they usually take about 12 hours at 225-250. I'll probably foil them for the last couple of hours. Then I'll let them rest for 2-3 hours in my hobo-cambro(old cooler).
I didn't inject any of them. Just covered them lightly with mustard. And, gave them a good coating of my rub.
I always pull them apart with my hands. I don't like to use forks or claws. Doing it by hand will let you feel the texture of the meat, and find the little chunks of grissel you don't wanna serve.
If I'm not serving until the next day I put the pulled meat in gallon sized ziplock freezer bags and refrigerate. To heat it back up I put all the meat in my counter top roaster and bring the heat up slowly. That's when I add sauce if I'm going to.
I've never tried a boneless butt. Dont think I would either. The bone helps you know when you're done.
Hope this helps
Shut Your Mouth BBQ
COS and a UDS