Very strange. I'd be surprised if the BatchUpdateCount had anything to do with it. The BatchUpdateCount property controls the number of commands sent back to the backend within a single submission (batch).
On the other hand, the Precompile SQL option could. Usually this option causes ODBC to create a temporary stored procedure on the back end. If ODBC create parameters with the wrong data type, you might see the numeric overflow error.
I'm glad you got it working and thanks for reporting the fixes back to the community.
-Mike