Here's one for the books.
I would like to get the newest iMac including the GTX 780M 4GB DDR5 GPU. This GPU is not on the white-list for After Effects to be able to see and use. When it will be added is a guess period, regardless of who you ask.
I was planning on getting Video Copilot's, Element 3D. They too have a white list. And this newest GPU is also not on their list. So I contacted them as to whether this GPU was compatable with E3D. Matt, the brother of Andrew, replied that this GPU was good to go.
So, I will be using one GPU that is both an unsanctioned GPU with the host program [AE] and a sanctioned card with the plugin, [E3D].
I am also looking at a build several hundreds cheaper with a 780 that is sanctioned by AE. Then everyone can be happy.
You misunderstand the After Effects white list. It applies to _only_ one feature: GPU acceleration of the ray-traced 3D renderer. The absence of a card on that list in no way means that the card is not "supported" for After Effects. It just means that that one feature won't work---and it's a feature that you likely have no reason to care about.
BTW, see this page for the update that we made that allows you to try to use that card for the GPU acceleration of the ray-traced 3D renderer:
If you use that feature, then you do put your system into an unsupported state, but only for that one feature.
As I said, though, you should not worry at all about the ray-traced 3D renderer. There are many better ways to do 3D in After Effects, including with Cinema 4D, which is now included with After Effects.