Flexibility probably wasn't the best word for me to use. What I meant was flexible in its role, 'filling in the hole' so to speak. I was actually planning to touch on this originally but left it out for being a little too deep down the rabbit hole. I'll try to keep my thoughts on it short, but the two main issues for me were having flexibility be a class' identity and the similarity between the new spells and spells currently in the game. SCH already has a few identity issues with AST over 2 spells, but the proposed changes would also turn Adlo into Regen and Succor into Medica II on a cooldown. Not that it wouldn't be fun to do, but I think if the class focus was that it could do a little bit of everything, it would struggle to find a place over healers with defined strengths because most endgame content is designed around 2 healers that can compensate for the other's weaknesses. Groups would have to ask themselves if a WHM can heal the best, and an AST can shield the best, why bring a SCH who does a little bit of each when they can just bring the best at each style together?
This is what I'd like to see SCH become and why I think its current strengths should be tweaked to highlight the shield aspect of their role. I'm not sure if it was intended or not, but almost everything here already applies to SCH. Adlo/Succor shield and heal, there is great oGCD healing in Lustrate and Indom, the only regen the class has is Whispering Dawn, support is fairly strong in Chain Strat, and personal dps is high. I'd argue it just needs to work out the kinks in its current kit and add a powerful health based shield that becomes the defining part of it, preferably through Selene.
In my ideal world, groups would look at a fight and say "This fight has tons of incoming damage/nukes/tight dps checks, we better make sure we bring a WHM/SCH/AST". Each healer ends up the best at something. But the problem right now is AST, just barely, is the answer to too many scenarios that SCH used to be the answer to. Their strengths need to be defined more clearly in ways that don't intersect, and I think making SCH the de facto shield class is one of the ways to do that.