Honestly, I hate the entirety of scaling buffs, and never understood why it goes over 10%, let alone 5%. But I came from a different breed I suppose.
At any rate, CHA = no.
I would say some type of Heal Power set focused on healing, but Heals are notorious for getting out of hand very fast. Plus we have several Gems, Passives and Runes to augment Healing.
Making the set CHA hardstats is a no from me for very specific reasons.
1: CHA increases too many combat statistics to ever be balanced at this point. The DEV's overloaded the stat with benefits because they wanted it to be useful, but when people like FS started crying about taking too many Crits, or that their HoT's were too small, well... they just straight over-did it.
2: Buffing, isn't a combat tactic, you pre-buff for a reason, because they last 15 minutes - 30 minutes. How frequently are you ACTUALLY going to say, dang, I'm so glad I was already in a buffing set and could just re-apply buffs instantly.
3: You essentially asking, for Gear that would make you heal 2x stronger, while retaining your Defensive capabilities. I know this for a fact, because any time, and I literally mean, every, damned, time, the FS get's even a slightest tweak that results in a reduction, they throw the loudest, most inane screeching tantrums you have EVER seen. And they will not, under any circumstances be reasoned with, you can only appease them by giving them what they demand, which in this case would be, you gave us CHA sets, but now we can't tank like a Knight, so we need both cause "SCREEEEEEEEEEEEE"
... and I'm not down for that.
Any rate. The only possible solution to this I could ever think of was to make Buffs a type of 'aura' effect that was constantly on, and applied to anyone within a certain radius of you [something like 50m or whatever]. The buffs would [...preferably] for ALL classes including Clerics] be 'normalized' to something like 5% - 10% [not a range, ALL would be the same, just pick numbers within that suggested amounts] and learned via skill-points.
Cause then we don't need buff-slaves. Clerics, could finally focus on their job, Healing, Resurrecting fallen allies, Removing negative status' etc. Would the CHA 'value' take a hit, course, but it'd STILL carry the negative effects modifier, DoT modifier, Critical Defense Modifier, AND Heal Power modifiers and personally, I think that's more than enough given comparisons to the other Base stats and what they provide.
Any rate, I personally, and TRULY, don't care in the slightest about FS, because of their demanding, entitled, obnoxious nature of crying like petulant children anytime they have to face the nerf-darts like the rest of us; and even mentioning them being even just in the slightest better off than other classes will set them off into a 'no we're not, we're weak, we need buffs, we need better gear' and any proposition that they be addressed in balancing? Lmao, you better brace for impact, because they're going to come at you with their hammers, sickles, Pitchforks and torches...