Replying to Question about gh3/4

Im shooting on a T2i right now, but I want to upgrade to a gh3or4. I know a few of you guys are shooting with one so ive just got a few questions.

My Lenses:
Tamron 17-50 2.8 non vc
Canon 70-200 4
Sigma 30mm 1.4
Canon 50mm 1.8
Opteka 8mm 3.5 fisheye

1. if I want to use the lenses I have already what converter would you guys suggest? metabones Speedbooter or just a regular one?

2. with the Metabones would there be vignetting with my wider lenses?

3. would it be worth switching to m4/3 glass or Nikon?

4. how have you guys found the camera in low light?

5. with a regular converter you cant change your aperture, so how do you compensate? low iso and bumping up the shutter speed?


feel free to post some edits if you have shot with either cam as well.