Actually, the only difference between UseModWiki 0.7 and WikiWiki is the behavior of the "diff" (difference) text. WikiWiki shows the difference between the EditCopy (the previous author's version) and the current copy. This makes multiple sequential edits by the same author appear as one edit in the "diff" output. UseModWiki "diff"s always show the last change made to the page. (When user preferences are added, the WikiWiki behavior may become an option.) Feel free to experiment using the SandBox page.
With UseModWiki 0.90, we now have KeptPages. Moreover, for a long time now, we've had UserPreferences? that allows one to select the diff behaviour one wants: show last author, major or minor diff.
A full VersionHistory is better for security. EditCopy is better for community. KeptPages is somewhere in between. Take your pick.
An alternative / orthogonal system is to keep the last copy that survived PeerReview; see StableCopy.