u can also be near the top healer as disc priest just healing
+ counting absorbs.. thats the most fun way to play, just spamming shields is stupid, and will get the talent nerfed..
also the first 7 bosses are quite easy, the later bosses will need more healing and spamming shields wont be that effective, since u will have to support heal too.
but yes, i have no problem being at the topheal list either, if healing+ absorbs were mashed together most good discpriest would be near topspot.
but a very good druid will always outheal u, since he can spam hots like u spam shields and since its counted as pure healing, he will be high on the meter, i hate the druid in the guild lolz preventing me from even shielding hehe. awesome healer.
shamans are the worst healers atm they should get buffed.
conclusion: your playstyle only works on easy bosses, while the titans and harder bosses will require u to preserve your mana. u will oom yourself too fast, and definatly wouldnt work well on hardmodes. spamming shields works wel up to auriya, depending on the other healers if they can handle it, u will need to support heal alot more.