Just recently decided to switch to disc to give it a go. As far as gearing and gemming goes, am I way off or have I got things right? Do I need to change some things?
Hmm... IMHO it really depends on the job you are assigned to do and how you go about doing it.
Your mastery is stacked for a shield spammer, which I personally don't love to do myself. If you're in Firelands, then you will find that spamming shield is not as effective as it was in BWD and BoT. I prefer to stack a little more haste these days instead, and I drop a lot of my spirit off, since I do not find myself needing the extra regen. If you can maximize your rapture cd and have enough intellect, then you should have little issue with your mana regen primarily from rapture, and depend less and less on spirit as you aquire gear.
My personal opinion is to find your playstyle and gem/enchant accordingly - I try to keep my stats balanced unless I find a need for one over the others.
Hi suspendedstasis, we actually have a thread made for this very purpose! If you hop on over to http://www.mmo-champion.com/threads/...iest-above-you! and post your armoury with some information (Do your raid 10 or 25? Are you on tank or raid healing?) then you'll get some feedback there.