Ouch. I do see the argument for compatibility with 22.1.1, and I could easily back off of `prog-mode`, but that also means you have to have to give up SMIE (23.3), which the Emacs devs have made clear to me is the path forward for indentation / sexp navigation.

Counter argument: Emacs didn't ship with a package manager until version 24, so pre-24, unless you were a part of the standard distribution, odds are you weren't getting much usage anyway. Do you know which Emacs Yosemite ships with?