Yes, if I would come back to C:S I would redesign the slipways to less than 45-degree angles and introduce a better geometric design for the left/right turn section in addition to curving the flyovers as you describe, made possible by the 1u trick to angle the slipway for a gentle curve starting from less than 45 degrees. http://imgur.com/dkbMYWn

I would also release some of my hidden gems of intersection design which I never bothered to make a release for... I hope some good DLC will come for C:S soon to inspire me to do this!

I see you went with a very similar design to what I'm working with. did you try curving the flyovers to pick up more speed and reduce size?