I believe you are right. My perception of Alldata was based upon: (1) my use of it briefly 7 years ago, (2) reading on a forum that it was based upon WIS, and (3) questions I have gotten from frustrated Alldata users who were looking for information that could be found on the DVD but not on the Alldata service. From what you write, Alldata content would seem to be equal or even better than the DVD.