C4d's are okay to use however you have to use everything to moderation. I think you used too many C4d's on this, that or you didn't blend them a whole ton with the sig.
Maybe try and blend them in a bit more, it'll create a solid BG for the render and IMO will look a lot better.

The text is a bit big too. Maybe make it a bit smaller so it isn't so distracting?

However you did an outstanding job on the blending, and colors.
As far as i can tell the lighting looks fine now that you fixed it up a bit. Nice job