GH4 + Speedbooster + Sigma 18-35 [The ultimate combination]?

Is this the ultimate combination for indie movie-making? The Panasonic GH4 records 4k, the Speedbooster “expands” your sensor and give your more light, and together with the Sigma 18-35mm f1.8 you are able to shoot video with aperture F1.2. The downside with the Panasonic GH4 compared too 5D mark iii and Sony A7S, is the poor video quality when shooting in high ISO. So using a fast lens is necessary when shooting in low light with the GH4. Last year, Metabone released the Speedooster, which is an adapter