With the advent of 3.1 drawing nigh, the mana changes will be going through. While it has been reported that those in raid groups of 25 will see little difference due to massive buffs, ten- and five-mans will be a little more limited based upon group composition. So, you see those gem slots on your gear that you've inserted spell power or spell power plus spirit into? Go ahead and replace those with mp5 or spell power plus mp5 gems (depending upon your needs). Ta da! You have your mp5 set.
Hopefully, Blizzard has learned their lesson from Sartharion 3D and ten man Ulduar will be attuned so that it is, in fact, easier than 25, so the slight dip in spell power will not be such a problem. And the boost in mp5 will make it so you do not need to rely upon group composition to make it work. This will also give you a healthy mix of gear to choose from should you come across mana issues or spellpower needs. And you'll already be one step ahead of other Druids, who may only do this when they have their whacked out terrarium-shoulder tier 8.
The above is wrong, and due to my own misconceptions. I admit its fallacies. However, holding onto your T7(.5) is still a good idea, as stated in the comments, due to having a Nourish bonus set. It's also good to have a set which has a lower repair bill for five mans and older raids.