Openly admitting to ignoring the players

[BooPoo]

Putting he facetiousness aside, in actuality, no, you wouldn't need to change how SGE heals. Because SGE's DPS kits heals people, so in a way this is where SGE ends up just adding a layer to this, if you're DPSing an enemy to heal somebody that I would say that doesn't count as downtime and counts as healing uptime. It's when you're DPSing to DPS that it is downtime. With SGE this becomes harder to measure.

Not meaning to disapprove of your final solution, I very much want it, but just want to add another reason against upping healer uptime to 90%:

Assuming no changes to healer kits, if healers have 90% uptime but sage is the only one that's able to consistently output damage during it (aside from Assize, Star etc. since those are like 400 pot per minute) then it becomes way too OP. Sorry but I can't fathom how SGE can exist in a world where everyone needs to be a curebot with balance in mind.