Saying that something increases body roll or decreases body roll is confusing. Especially when decreasing body roll can result in less traction at that end and increasing body roll can result in more. Or maybe it doesn't? Then you also need to consider that a particular setup isn't only based on the track but also the motor used and the speed on that track, which is where things get really confusing. You may find that a higher average roll center works well on a track when you are running a 17.5 in blinky mode but is undriveable on that same track with a 7.5T in unlimited, where you might prefer a lower average roll center.

It's best to stop thinking in terms of increases or decreases body roll in regards to settings and think more along the lines of what is it doing to camber gain with suspension travel and what effects does that have?