Bento Data Source is still in the list of menu items for File…Import Records in FM Pro Advanced 13.0v3. I don't know if it is also in FM Pro but you can download the trial version to check. (There is also the Bento 4 to FileMaker Migration Tool: http://help.filemaker.com/app/answers/detail/a_id/12105/related/1)
I am using FMP13. All the data in it comes from Bento 4, which I transferred using the Migration Tool. But in addition to this I have imported other data from individual Bento 4 libraries manually - all without any problems.