At the moment, with some decent gear and buffs, it's totaly possible to spam at least HL R9 without ever going oom. I am doing it myself and have to admit that it seems to be ab bit op, most of the times i don't even have to drink a manapot or use a flask in order to spam for 10 minutes on a Hydross fight, a decent Shadowpriest and some elixiers is all it takes.
With the upcoming nerfs ( Illumination only returning 60%, Spiritual attunement not giving mana on overheals, Shadowpriest DPS nerf, and all elixiers and flasks nerfed to a level where it's questionabel if the use of those makes any sense at all) this will propably no longer be the case.
Nevertheless I think healing as a pally will be much more fun after the patch, no longer being abel and forced ( since it's saver to do so ) to just mindlessly spam heals, I will once again have to put some effort into it (watching for overheals etc.) and healing will be much more demanding as it is now.
I'm not happy having the healing capability of my charakter nerfed, , but I think it will be very possibel to live with it. Pallys will remain the best singel target healers even after the upcoming nerf.
Eh, I realize you're not a native speaker. You shouldn't be held to a standard of flawless spelling and grammar. Please do try to read over your posts for typos and such before submitting, though. Thanks.