You could try Landxml which may be better than genio exports? http://communities.bentley.com/products/road___sit
I sudgest only using the one to design in, only share data for information and for others to tie into.
Edit: BTW, Civil 3d does not differenciate alignments like MX, we only have Alignments.
As I said previously. Do not move over existing current projects to Civil3d, only start new ones or use data as prevously designed as As built information to work from.