Allow use of all learned skills (at lower efficiency) if level synched...

[Fevelle]

Do not forget that they get Leeches only at level 40, which makes some dungeon quite hard to heal through (like the Worm Boss on Cutter's and that Sludge DoT), making Eos a crutch until then

Not really since Galvanize effects act like a sponge to the DoT damage, hence preventing any trouble with it. That, combined with Eos' AoE regeneration is far from lacking in comparison to the other healers.