I couldn't get MasterControl to work over Bluetooth with my HTC One M8 (And it pairs with a classic bluetooth keyboard just fine), but I can fiddle with it more later. But I suggested something like an ICP3 using Pandora parts in another thread back when, and I'd totally be willing to shell out up to $150 for a case-with-phone-holder and HID Bluetooth/USB PCB inside either Pandora or Pyra-Based. Pyra based would be even cooler, as one could in theory buy the screen parts and PCB to upgrade to a full Pyra later if you so chose, or just buy a Pyra and use your Pandora/Pyra based ICP3 with the full-blown version!
This would definitely be one project I would totally be onboard with a Kickstarter or something similar from a crew that is known to fully support their customers as ED and Co do!