My experience in high end content as SCH, AST and SGE wasn't exactly interesting from a role gameplay point of view.

The fights themselves expect coordination, memorization and sometimes a bit of reflexes from each role, being DPS, Healer or Tank. There are intricacies to each role of course, like Tank carefully repositioning bosses and healers coordinating their oGCDs. And in general the 2min burst window gives every class (Or forces every class) into a coordinated rotation.

That being said, within the healer role, mechanics quickly get dull: As you progress in a fight and learn its damage spikes and movement, you'll naturally find more filler space.

That is true of all content, whether its Dungeons, Raids or High end encounters. (Although arguably the uncoordinated and randomized nature of raids with new players makes it so that you'll be changing some of those Damage GCDs for Raises.)

Ultimately, healers don't have much in terms of gameplay mechanics to their jobs and while in high end you're distracted out of that fact by the mechanics of the fights themselves, in the end you will go back to Glarebroiling over and over.