For another there was a need to interface back and forth between ACAD and Microstation based applications.
I add that "left hand" comment because I found that Microstation is (was) a click-happy software that doesn't leverage (or even allow for the most part) the use of the left hand; if you are a right handed person, of course. (Hey Bentley, not only do many of us have 2 hands but we have this new thing: it's called a keyboard.) For all the lefties out here the converse would be the case, but I digress.
While checking over my links, I found that Autodesk Labs has a DGN/DWG converter!!! So if you are in need of such file conversions between DWG/DGN then just click on the picture of the Labradors below...It will bring you to the Autodesk Labs site; you can download it from there.