While I flail confusedly amongst the waters of various options for my poor bored healer, the only regular things I have been healing have been 5 mans (groan). I haven't been playing much during the week, because I've been suffering from the mild affects of seasonal change (i love leaves changing color, but my ears, nose, and throat apparently do not - and who would have thought that quitting smoking would make all these pains even WORSE?). So, my healing has been reduced to only five mans and the occasional weekend pug.
Greater Heal is mainly useful as a tank healing spell. Therefore, in a raid where holy priests are usually assigned to a raid healing role, it makes sense that Greater Heal gets little use, and therefore renders the talents associated with it as wasteful if there are better options. After all, if you intend and expect to usually heal the main tank in raids, you really ought to respec Disc, who get more benefit from Penance than Greater Heal anyway.
Do you have any questions about Holy Priest specs? Want some guidance as to what talents to choose? I am happy to help! It's quite a bit of fun for me actually. Shoot me an email at my new email address, missmedicina at gmail dot com, let me know what sort of content you usually heal, what other healers are in your raid (if you raid), and I will do my best to advise you! If you permit me, I'll even post it here so that the rest of the community can give helpful feedback (please note that any rude or disparaging comments will be removed - if you want to be mean, check out the forums, or comment on wow.com ;)). I'm not as good with Disc specs or other classes, but I am still interested in hearing questions or feedback about them.