I've been busy at work this fall so I don't have time to work on my own engine as often I'd like to. Anyways, I'm happy to share that I now have a working Metal renderer (both iOS and OS X). Using MetalKit I can do the view setup identically on both operating systems and there are very few different code paths. D3D12 renderer is progressing well. I'll also implement Vulkan renderer as soon as public implementation becomes available.
VR rendering needs more love. I'm naively rendering the scene twice. For example culling and shadow rendering can be done only once. I don't have my own HMD yet but borrow my employer's DK2 sometimes. I'll also add Vive support as soon as possible. I started making a VR game on Unreal Engine to get to know VR and Unreal better. It's a System Shock inspired space ship exploration game. The plan is to utilize Vive's controllers or Oculus Touch to interact with computers, drawers etc.
When implementing new APIs I'm focusing first on getting things working and later making the implementation as efficient as possible. For example, I'm using only one command list in my D3D12 renderer but will add more soon.
Visual Studio's and Xcode's frame capture has been very useful in debugging these new renderers and to make things easier I've added debug names to every API object.
Next year I plan to hit Aether3D 1.0 (0.5 is now under development).