I think the data that you need are available only through object model (have a look at our tool; it makes available "who has what checked out" and "check out history of an item" data).
As for data that are available through the cube, look up the following article in MSDN. While that does not give you current check out status, I believe the cube has sufficient data to build a history report (through file and changeset tables).
The temptation to get dirty with relational database is almost unbearable, but I personally resorted to make maximum use of object model and code churn cube. As of now, the data there were sufficient.