Regarding Chris Lilly's injection, this is what I posted on his pork shoulder recipe thread last summer:
"For those that think the injection is too salty, try KOSHER instead of table salt or simply cut the salt back a bit since table salt is cheaper and dissolves quicker. On another note, ADD 2 TB LEMON JUICE. Even though it's not published, that's what Chris Lilly has been teaching in his classes. I recently saw that posted somewhere and sure enough, had it confirmed on youtube. My last pork butts were with the added lemon juice and 1/4 cup kosher. Some of the best BBQ I've ever made, and my sister described it as "AWESOME"!
There's lots of issues with injection. I've never noticed the injection affecting the bark. Maybe it does a bit if you inject right before the cook, but I usually do the night before and can only assume that whatever injection is gonna leak out already has. I carefully put the butts on fat down and don't touch unless to wrap. If leaking injection has washed some rub off, it would be a good idea to sprinkle on a little more rub where needed, even after putting the butt on the grate since the meat should be wet, anyway. By the way, if using an injection, don't use a rub with too much salt.
One thing that to consider is how much of a brine effect the injection has, and I'm not sure that I get much. As to moisture, it might seem like it does, but moisture comes down to how well the meat is marbled and cooked. Like with any other bbq cut, pit moisture and foiling can also help.
What the injection does for sure, though, is add FLAVOR. The issue is trying to get the butt to retain the injection long enough to make it worth the trouble.
I'm always up for injecting tips, because we can really taste the difference when enough of the injection stays in the meat. My wife has been injecting turkeys for frying for twenty years, so I often try to get her to do it. Sometimes though, like last time, even SHE can't get it right. I can pretty much tell whether the injection was worth the trouble by how much liquid is in the pan after applying the rub, and I guess I need to start just re-injecting and re-rubbing if needed. It's just annoying since usually I like to inject and rub the night before to cook the next day, starting in the WEE hours before I've had my coffee.