Gary, are you in a food coma? How did it turn out? It looks delicious from the outside.
Sorry that it didn't turn out as good as expected, but that's how you learn. I wouldn't brine a pork butt because it will turn "hammy" on you, rather I would inject the night before cooking. Good luck with future cooks and don't let this one discourage you.
I trim down to about 1/8" and cook fat cap down on the WSM. Definitely remove any hard fat on the butt because that will never render off. I never brine anything except poultry. Don't usually inject brisket either, but many people do inject.
Most people enjoy the crisp bark, but you should definitely cook what you enjoy. Experiment with pork butts because they're much cheaper (here in the states it's around $1.50 (US)/pound for bone-in. Cheaper on sale.)
I still consider myself a beginner. They're plenty of more qualified people on this board. The next time you start a cook thread that is picture intensive, put it under the photo gallery section (I'm surprised this wasn't moved there yet). You'll get a lot more response.
I've never had to tie a butt up. It should be all one muscle. Also don't get to hung up on temp. Tender is more important. Once you hit 190-195ish, start probing the meat for doneness. IT should feel like a hot knife...blah,blah,blah. You want very little resistance.
However, some butts are just dry. Finishing sauce if your friend at that point.
I agree with JPowers, I think you may have trimmed to much fat.
Yes - I was definitely caught up on the temp... I think maybe it should have come off sooner and yes more fat next time.
We don't typical buy actual "pork butts" in the UK - I guess its the ham. This one opened up and would have gone quite flat... cheap supermarket crap. I am going to costco tonight - they usually have good meat in the UK.