What is the purpose of using IBIP when it is preferred over other mass uploading functions .
IBIP has been around a long time (back in the older 3.0 versions) and was specific to PM and PS only. The main function was to upload and download data.
LSMW is relatively new and encompasses all modules. Much of the IBIP functionality is incorporated into LSMW.
One thing IBIP is very useful for is to download the data into MS Access from where you can run lots of reports and generate charts etc.
However, LSMW is the preffered method of data transfer.