In my experience micro 4/3 cameras are inherently noisier than their larger sensor and, more relevantly, larger sensel brethren. I have the Olympus OM-D EM-1 and the GH4 and they each exhibit more or less equal noise at various ISOs shooting raw photos or video (on the GH4).Regarding the GH4 and video, shooting at ISO 200 preferably and no more than 800 or so helps as well as leaving NR=0 in the profile. I’ve never felt the need to de-noise at 200 or maybe even 400 but 800 and especially 1600 start to benefit from it. There was a lot of discussion on this on DVxuser.com without any magic bullet that I could tell – other than the obvious of use more light. Someone looked extensively at the different photo styles and they didn’t vary much in their effect on dynamic range tho I believe cine V and natural were around 10 stops with all the others 11 or so. Using a 360 degree shutter angle at 24 fps also helps in low light conditions but, of course, causes more motion blur.
I also had to learn to not try and bring up the shadows the way I was used to doing with my D800E. The good thing though with video is that noise isn’t as noticeable/objectionable as it would be on a still photo as long as its film like with people advocating denoising up front in post and then adding in film-looking grain at the end. Lot’s of possibilities.
Bob