Are there any caveats for using the same idiom within modules...

I can't see any caveats for using it within modules. It is the modules author's choice to permit or restrict the (arguably unsafe) "." in @INC. I'd consider modules relying on "." inside @INC to be broken. They shouldn't rely on "." but use something else to get their location, e.g. FindBin or __FILE__ or such - if they are not explicitly chameleonic modules.