The problem with JVC LS 300, IMO, is that it wasn't offering several features of the GH4 (auto focus) at a much higher price (point) and because it was a sub-4K camera with MFT glass.
For me it was the low DR of their sensor and no LOG profile when the LS300 first shipped. The LOG issue was fixed, but the lack of DR from their sensor was something I was not willing to put up with. ( GH4 sensor has always seemed much better to my eye )