Someone in the Buffalo NY area sold an M400 on craigslist earlier this summer. They had that bike legal and registered. I don't know if that helps at all, but there's at least one stateside and on the road. Good luck.
It helps IMMENSELY if someone else has already converted one. You can use the same letter of conformance.
Bingo!
**Edit
Something tells me they did a frame swap. The list of eligible vehicles (i.e. previously converted foreign vehicles) does not show the M400. The differences in the 600 and the 400 models are minimal, they could have done an engine swap.
http://www.nhtsa.gov/cars/rules/import/elig123109.pdfPage 8 has all the Ducati models that have been converted to date. If it is not on the list, that doesn't mean it can't be imported and converted, only that its eligibility is unknown -- and it has never been imported legally.
