At least in ST, I've noticed more and more WTM using stoneskin instead of cure on the tank. When I ask him to actually cure he is wasting mp. He asked why and some other dps said that stoneskin was easier on the mp than cure and cure II and that there were a bunch of healers doing it now since it was an mp saver.
So me being a jerk and the second healer just popped stance and remained in it as I watch the raid nearly wipe several times, I only came out of stance to save us from wiping. I went the asshole route for that one.
We were also lucky our tank didn't MT.

So what are your thoughts, is stoneskin in the middle of raids easier on mp than curing?