Any reason not to package-install it? Especially when using the use-package sweet, sweet syntactic sugar? As a Debian user I don't see too much point in using system -wide packages with emacs.
i don't think the security model of package-install is good enough for my thread model. (to be fair, i still package-install some stuff, and, yes, with use-package, but i'm trying to eradicate that practice.)