A week of reflection has created some perspective...
This was my first packer but my second brisket. The first was a highly trimmed flat using a smokenator.
Frankly, this packer was more moist but less flavorful than the first smoke. It wasn't smoky enough. Why? I'm thinking less fat simply means more smoke and rub flavor. All that fat improves moisture but "protects" the meat too much.
I learned long ago that leaving the fat-cap on is a compromise of higher moisture retention, slower cooking for more tender meat, but in most every case, reducing smoke penetration/reaction on the fat-side to null. You may want to try trimming-up a packer and leaving just thin strips of fat...just enough to do a bit of sefl basting...smoke can still get between the fat strips, so a bit more smoke to that side of the meat.
I'm thinking the best of both worlds is to remove as much fat as possible, inject, and cook low to get 7+ hours of smoke on it.
If you inject, beware of the danger-zone times/temps as it can no longer be considered intact whole muscle meat at that point, and lower temp smoke chamber won't get you through the danger zone in time (41-135* in 4 hrs) to be safe. I don't inject brines or marinades into ANYTHIING that's fresh meat anymore just so I can stay within the intact whole muscle guidelines...brine/cure injection would be the only exception for me. Also, if the meat is boneless (example: pork shoulder/butt), the boned areas (any place that's penetrated by a knife, etc) need to stay open when cooking, then it can be considered whole muscle as well.
Just the thoughts of a novice.