In my opinion, the BMCC is really more of a professional production camera. The BMCC records internally in ProRes 442HQ and RAW uncompressed; the two highest quality codecs available. The Sony nex vg 900 has internal compression rate is 28Mbps though, you can run uncompressed 1080p out via the HDMI output.
In ether case, be prepared to spend money on all the extras you’ll need or want; case, lenses & light control, like filters, mattebox, flag; batteries, mounts and/or cages, especially with the BMCC.
Dave J