Did you find a solution for its file size? For my side-project I had to choose between c3js and flot, and while flot was 56KB + a few KB for some plugins, c3js + d3js was 300KB. JQuery was already used and thus did not count against flot.
C3js made a good impression otherwise and flot seems to be dead (no activity on https://github.com/flot/flot, or is there a living fork?) making that decision hard.
Unfortunately no. We needed d3 for some other things so it wasn't a concern. C3js development doesn't seem to be very active either - hadn't looked at it in a while -, but it's still a pretty good library.
