there are three version sof dix to download: lite (free), full with ads (free), and full (non-free).
the full versions offer tools and utilities to convert and compress existing files, while the lite offers only the codec. with the lite you need other utilities (MAX, premier, etc) which then use the codec to compress the files for you.
so to answer your question, no the pro version does not offer anything above and beyond just the normal codec if you are only going to use it inside of max. if you want a separate 3rd party utility for avi compression, then yes the pro version is for you.
here at work all of the 3d guys have adobe premier and MAX, which negates the need for the full-blown divx package. as such they all just get the codec which they can just select from the list of compressors in either utility.