Here's an interesting new Quick Release Top Handle that uses a slotted mount to fit a variety of cameras including the BlackMagic Design Cinema, or 4K Production cameras, RED Scarlet, and EPIC. The Quick Release handle can be removed by sliding it off the sides by depressing the safety pins.
The QR Top Handle uses a leather design, and can be adjusted left/right along the rail for perfect center of balance on many different rigs. It's not cheap, but it's a very flexible design that can be used across many different cameras and rigs. It basically just requires a flat surface with 1/4 threads regardless of where the threaded holes lineup.
If you're thinking what i'm thinking, this also means it can be mounted to fit a variety of different DSLR Camera Cages. Check it out at (found here).
QR Top Handle for BlackMagic Design Cinema or 4K, RED Scarlet, EPIC, Cages