I spent a lot of time doing carving experiments and switching the stances back and forth. I found the major problem I was having with the wide stance. In case it helps someone else, here it goes...
I was rotating my hips slightly into the turn (ironically, from what I've read, it's supposed to be helpful), which caused my back leg to rotate along with the hips (can't keep it in place with the wide stance - end of movement range). That resulted in more rockering of the board and in weight shifting through the turn being more problematic.
While I thought, I was getting more angulation with the narrow stance, that's not the case. With being able to de-rocker the board, I had more speed/larger turn radius and simply more inclination.
When everything worked right, I was able to get nice pencil-line carves with the wide stance, but things are quite a bit more finicky and really intolerant of sloppy technique. Not staying extremely focused and the tail starts washing out a bit...
What was quite noticeable is that edge transitions were snappier/cleaner/faster with the wide stance.