The killer feature that would make the BMPC excel even more than it does at the moment would be a waveform. The main thing that I feel the camera is lacking is exposure tools, a histogram and zebras just doesn't cut it.. I know, easy solution is to get a proper lightmeter, which I'm planning to do either way, but a waveform (or false color for that matter!) would perfect the camera in my eyes.
I don't care about HFR, there are other cameras for that. I believe very firmly that no single camera can be the perfect camera for anything, so there's no point in asking for amazing new features all the time.
With the 2.4 update I feel like the camera is finally ready for production and I'm looking forward to working with it a lot more!