Teigha? technology supports both version 8 of the dgn file format (as written by MicroStation V8 and V8i) and version 7, and can translate a wider range of dgn objects.
Basic technology is restricted to dgn version 7 and a smaller range of primitives, but does include some facilities not available with Import-DGN's Teigha? facilities.
It depends on your requirement purely with proper combinations.