Would a change to 38% mean that his current $4.28 earnings (on the comment above) on 9 upvotes be around $163 under the proposed change?
No it doesn't mean that, because voting behavior will change. Most likely there will be a lot more voting on comments and more comments being rewarded so the $163 would be split up a lot more ways. Also probably more comments (both good and bad).
You can not evaluate actions taken under one set of rules as if they would occur unchanged under a different set of rules.
Very True, I tend to only vote on the comments made to my posts, in hopes to gain readers, if there was no limit or a different limit to voting on comments I would vote on many more comments, being some of them to me add value to the original post.