These two lines made me register for these forums to post on this. In a raiding situation where you're not a tanks sole healer (you never will be) you probably will only use a few GHs the entire fight, alot of PoHs, and you probably shouldnt be speced into evang/arch/attonement. The talent points can be far better when used elsewhere considering how terrible both are in terms of heal per mana.
As for renew, using renew is a playstyle difference. Ive done some heroic fights where renew was my #1 heal, and Ive done others where I maybe cast it 10 times in 6 minutes. Its a very useful heal and is especially useful when you are building up DA shields on someone (generally before a fight but not always).
People tend to be overzealous when they're talking about what to do for playing something, with how the game is set-up right now what YOUR playstyle is will determine how you play your spec/class.