How should they address the disparity within the role?

[Aravell]

To be fair even in that situation SCH still was played 3 to 1 more times than SGE.

AST and WHM can be fixed with damage niches (because regen healing is inherently useless), but the entire game is designed around the output of the shield healer and SCH is just such a better shield healer than SGE

I think they could give SGE a niche if they went all in on the damage healer aspect.

If, for example, SGE has less mitigative tools, still enough to clear, but they have instead vastly superior damage over SCH.

So in this case, with a SGE, you'd just barely survive mechanics if mitigation is perfect but you have a larger leeway on the dps check. Meanwhile, SCH doesn't provide the large leeway but you have a much safer run overall.

That way, SGE gets a niche filling in for lower total dps teams or speedkilling, while SCH remains the more generalist barrier healer. It wouldn't make SGE a vastly popular pick, but it would give them a niche to shine in.