How much out-of-5-second mp5 can I realistically expect to lose when 3.1 hits?
Short answer: A lot.
Long answer: A lot. You'll be losing about 300-400 mp5 out of the 5-second rule, and yes, you're going to be feeling it. My Resto set is by no means best-in-slot, but I can get through any 10-man or 25-man fight with the possible exception of Sapphiron without having serious mana issues. Point is, Blizzard means it when they say they want raids to get better about avoiding damage, and healers to get better about conserving mana. Between the Oo5sr nerf, the Lifebloom change, and the Nourish buffs, it also seems as if they're moving Druid healing in a more reactive and less proactive direction -- or, if that's not what's actually intended, that's the playstyle that these changes incentivize.
How much armor in bear form can I realistically expect to lose when 3.1 hits?
Short answer: A lot (see a pattern here?).
Long answer: We've technically already answered this one but I still get it frequently. I lost a little bit shy of 6,000 armor in the transition to the PTR. Due to diminshing returns on physical mitigation per point as you approach the armor cap, at higher gear levels you'll feel this less than you will if you're gearing up.
Is the new Eclipse worth taking?
If you're using Eclipse now, yes. It's an out-and-out damage boost to the Wrath component of the talent in its current form. If you're not using Eclipse for the reasons that people typically give for not taking it (i.e. too random, too inconsistent, and too difficult to keep track of), nothing about the talent's actual function, its proc-within-a-proc, has changed.
It has become more compelling as a damage talent, and the Starfire component will become increasingly valuable as: a). Moonkin crit rates improve, edging us closer to a guaranteed crit, and: b). Starfire is our best-scaling nuke anyway, so you're fast running out of reasons not to take Eclipse. Do yourself a favor and download SquawkAndAwe if you're not already using it; it'll make things a lot easier.
More on this in a little bit, because Eclipse reappears on the Balance tier set bonuses.
Owlkin Frenzy got changed, then changed back, then -- huh? What? Huh?
Yep, Owlkin Frenzy was initially changed so as not to proc from anything but melee damage, which rendered the talent all but worthless for PvE raiding. Luckily, it was changed back, so the Owlkin Frenzy on live is what you'll see in 3.1; I think it was Ghostcrawler who rationalized that if moonkin wanted to take damage deliberately in a Tier 8 raid to get the DPS bonus, they were free to do so provided the heal team could (or wanted to) keep them up.
I'm glad they didn't change it. There's enough random, completely unavoidable damage in raids today that you could have justified keeping Owlkin Frenzy the way it is just for that, and from what I've seen of Ulduar so far, you can expect more in that vein. Also I adore the outraged squawk that the proc produces.
Did anyone get the license plate on the truck that hit Lifebloom?
No kidding. Lifebloom is...well, Lifebloom is very sad right now. It is off in the corner by itself sucking its thumb, listening to Evanescence, and refusing to play with the other HoT's. More seriously, you can pretty much kiss rolling Lifebloom stacks on multiple tanks good-bye unless you're OK with the idea of going OOM within 2 minutes, which is a pretty huge nerf to the current Restoration playstyle in a raid. While healing the aforementioned Kologarn attempts, I tried rolling Lifebloom stacks on two tanks and was horrified to see fast I could blow through my mana bar.
Lifebloom's current cost on the PTR is a ghastly 929 mana (for reference, Regrowth costs 921 mana, Rejuvenation costs 572, Nourish costs 559, Wild Growth is 804, and Healing Touch is 1026. So out of the heals you're most likely to be using (unless you have all of the Healing Touch talents and are using that, glyphed or unglyphed, as a tank/flash heal), Lifebloom is now the most expensive in your arsenal if you never allow it to bloom.
What's up with the spaz-tastic Tree of Life form animation on the PTR while chain-casting?
Noticed that too, eh? Try chain-casting any direct-healing spell and you'll see that (at least on Tauren tree form) the tree seizes up halfway to its "Look at me! I finished casting!" animation and goes back to casting. Whether this is a bug or intended, I'm not sure, but it looks too weird to be intended.
So Thorns scales now?
Thorns damage is now getting additional scaling from the spellpower of the caster (as opposed to the spellpower of the person on whom it is cast). This has obvious PvP implications for Balance (and potentially so for Restoration, depending on which talents you take) and also means that ideally you'll want a Balance or Restoration Druid, and only a Balance or Restoration Druid, casting Thorns on your tanks in a raid.
I'm happy with the buff but confused somewhat by the execution. It's fairly irritating from my perspective as a bear tank as Thorns is a 10-minute buff when cast on others, and for 5-man work it's entirely possible that I will be dragging along my Balance or Restoration set in order to cast Thorns on myself before switching to whichever combination of Bear/Cat gear most suits the instance or individual boss fight. The Thorns change makes sense from a PvP perspective, but from a PvE one, I just don't get it. The spec with the most potential PvE benefit from it (Bear -- you should not be taking melee damage as a cat, moonkin, or tree in raids or 5-mans) won't get it at all unless we set aside yet another bag's worth of gear or depend on someone else to refresh it constantly.