Just ran across this article... I agree! Very nicely done, especially with the page-level proofs!
As a bit of a sidebar, the reason why such a small change caused the Clustered Index to initially double in size is because it caused every row to grow a little. Since the pages were as full as they could get, it didn't take much to cause every page in the index to split. Here's what that all looks like... notice the fragmentation percent and the page density... (and I used the DBO schema in a "scratch" database for the test).
Here's what sp_IndexDNA™ looks like for that index (all the pages of the index are about half full).