This works well in the current situation where mana is not an issue, but will probably not be an issue in most encounters at 80 due to wasting so much mana. Also, i assume you didnt count the final ticks for lifebloom, as the final heal alone heals for more than your listed value atleast for me.
Your Lifebloom bloom heals for nearly 4000 at level 70? I am impressed by your level of gear then.
I did not include crit on them however so it should err slightly higher but generally bloom healed for around 1.8k if I recall correctly when I did that.
The mana thing is irrelevant at 80 due to costs being base mana related, if 2 people need healing it is cheaper, faster and less GCD consuming to use WG than to use 2 of any other spell - and you get 3 other applications bonus too (normally).
Smart healing WG is great if you are the only one raid healing, having more than us doing it and the people who get WG will get the CH or CoH ticks as well though which is the bad part.
The difference between nerfing WG previously was the fact it was nerfing only WG and nothing else, doing similar nerfs to all forms of popular AoE healing should be less of an issue (although not from a WoW forum whine point).