Nature's Swiftness now also increases the healing done by the affected nature spell by 50%.
I did some testing on live, and when I already have a hot, my HT hits for about 23k (without a hot, it's about 20k). I have 7446 spell power and 12.31 mastery.
So, is an additional 11.5k of instant healing on a 3 minute cooldown worth the talent point?
I poked around with the 4.1 talent tree posted on Wowhead and I think that the choice is between NS and Perseverance. Looking at WoL for the past raiding week, I pulled out the magic spells that I took damage from and compared a 2% reduction in damage to the extra healing I would get from NS (considering how many times I could cast it in the length of the fight).
For all of the fights I've done so far, NS came out ahead (in providing more healing than Perseverance prevented). Plus, NS+HT can be cast on anyone while Perseverance only prevents damage to myself, and I can get onto my next spell faster, since I only used a GCD to cast HT, not the full cast time (2.3 seconds for me). On the other hand, Perseverance is a passive damage reduction, while NS+HT requires the use of a GCD.
There is an argument for preventing damage, and resto druids have very few tools for that. Still, I think the flexibility of NS+HT argues for it's use (even if you aren't tank healing, having the emergency cooldown is helpful).
The other possible place for that point could be in one of the talents that buffs Rejuv. I am still horribly abusing Rejuv (and my mana is showing it), so it's hard for me to judge that based on my current performance (if I buff Rejuv, I'll continue abusing it... that's a bad cycle). I know that some of my abuse of Rejuv has to do with learning the fights. As I know the fights better, I'll have more control over my movement and won't resort to instants as much.
I have 3 points in Improved Rejuvenation, and I'm planning to keep that. It buffs Rejuv and SM (and thus, Efflorescence), but Blessing of the Grove and Swift Rejuvenation are talents that I'm not sure if I need for 10s.
I'm planning to review my logs after this week's raiding and will decide after I see my Rejuv use on the fights that I have a better handle on (Magmaw) as well as the fights that I'm still learning.