Currently I am unable to build my app as arm64-v8a due to FMOD folks not providing arm64 libs. They said they'll fix that issue: http://www.fmod.org/questions/question/arm64-v8a-and-fmod-fail/
I assume that Audio SDK plugin for FMOD (Android) is 32-bit only.
Because all Galaxy S phones (the ones for Gear VR) are 64-bit and OS is 64-bit afaik too. I've read somewhere 64-bit apps perform better on 64-bit ARM systems. So, I am just hoping to squeeze out more performance for Gear VR going 64-bit all the way (that's if the information about 64-bit performance over 32-bit is true)