I think, it's better to render proposals in "hide differences" mode by default (and have button "Show differences" by default).
Ideally, it also should shown only the last version. StackOverflow is a good example in this regard — it shows the last version, and provides a link to the versions history, diffs, and to each past version individually.
But there is a question what to do with comments to the past versions. A possible variant is that the past versions are just folded, and the comments are shown as was before.
I think, it's better to render proposals in "hide differences" mode by default (and have button "Show differences" by default).
Ideally, it also should shown only the last version. StackOverflow is a good example in this regard — it shows the last version, and provides a link to the versions history, diffs, and to each past version individually.
But there is a question what to do with comments to the past versions. A possible variant is that the past versions are just folded, and the comments are shown as was before.