I found a collection of reports printed in 1851 - First Regiment of NY Volunteers upon their return from Mexico.
It's not a complete list of the regiment and they acknowledge that it's not even a full list of men entitled to receive a medal but I thought it might be of use to someone. "The returns, as made, are as yet imperfect, and cause some dissatisfaction to the relatives, as well as the disabled, but returned volunteer."
The ancestor I happen to be looking for is mentioned in Bancroft but not here, guess he wasn't a where's my medal type of guy.
I only skimmed the book but it contains funeral arrangements for officers, parade routes, eulogies and it describes the medal and gives the name of the artist, etc. Really interesting stuff. http://archive.org/stream/reportsofspecial00newy#page/74/mod...
Edit - I just noticed that the owner of the book counted up all the men listed in each Company and on page 76 notes - "The names left out of this list would make the entire 'something' of Company A, say 78 men"