The git idea's pretty interesting/clever.

Then again nothing says you can't whip up a new local::lib sandbox directory and install your new stuff into that and prefix that new directory on PERL5LIB. That'll let you combine possibly upgraded dependencies and still use the normal tools to manage installing everything. If/when you decide to go with the new version you just go back and install into your "normal" l::l directory.

(And I really like the git idea.)