Some of the capabilities within VIPP that I have not been able to address or atleast not easily using Fusion Pro to output VDX, PPML, PS or PDF include:

1. Page numbering (ie. you have a cover and a guts page the guts page repeats 100 times) how do you create a page number on each page when using a javascript rule to loop the 100 guts pages?
2. Complicated page numbers like adding roman numerals, alpa-numeric combinations, etc.
3. Output composition data / reports. When your data file determines the number of pages or even the number of pages of each type, in VIPP you can write out to a log file the details of a composition per record. This is important if you need to manifest or bill based on that data. The only thing I have been able to think of is an upstream preflight application to generate that data.
4. Greater control / capability of media calls. Even media calls based on the data file or calculations based on page number and data file calculations.
5. Overall simplicity for recurring work requires a considerable hardware / software investment.
6. The ability to skip a record based on missing required data and write to a log an identifier from the data.
7. Though reflowing of text works well with fusion pro, the ability to call segments of text from a library of text files (or the like) as something other than images.

These are just a few to get started. I am hopeful that I discover that each of these are possible without VIPP and I just need to do some more learning, but we will see.