While shooting an astral time lapse one night with my Canon 6D, I had my FS7 standing by to shoot the sunrise. I did some test shots of the night sky, very dark, moon-less night, and it was crap. Had to crank up the gain. I deleted all that footage. The 6D does a nice job and my lens of choice lately is the Rokinon 24mm f/1.4. I have the Canon 14mm f/1.4, Canon 16-35mm f/2.8 as other astral time lapse lenses, but the Rokinon seems sharper to me and I like the manual iris ring (oh, and the non-Canon price). The FS7 did a nice job once day break came along, really nice dynamic range for those subtle color gradients.
Off the top of my head (as a 5Dm3 & GoPro owner, who's shot quite a few night timelapses), I imagine that even a relatively slow lens like an F2.8 would give you cleaner images than the GoPro. Especially given the greater pixel-count and possibility of NR in post.
Try a test of reflected streetlamp light on the sidewalk, the results should be pretty clear.
Sigma 35 1.4 and 50 1.4 with Speedbooster is your friends.
I had zero issues shooting in candlelight and blowing out the candles completely. I used the a7S for starlight shoot on this doc, but i imagine if you want best results, this lens combo will get you there the sharpest with least amount of cash.