Firstly, Term::Readkey is a pretty small module so it's no great overhead to install and use it and it seemed to do everything right whenever I used it. My advice would be to go with that.

It's not much overhead for the processor or RAM, but it's a fair bit of overhead for someone who isn't a Perl programmer and is thus unlikely to be familiar with the task of installing nonstandard Perl modules. It's more end-user overhead that I am to avoid, rather than system overhead, in this case.

As things currently stand, I have a workaround built into the thing so that it uses Term::ReadKey if it exists on the system (using an eval), but it's pretty kludgey, and it ends up having less slick, intuitive behavior for the less technically savvy user as a result -- pretty much the exact opposite of a desirable state of affairs.

As for your example code, it unfortunately looks pretty environment-specific (POSIX::Termios makes me think so, anyway). I prefer to avoid assumptions about the operating environment as much as possible when writing stuff like this, where its usefulness is not limited to a particular OS by definition. I appreciate the attempt at helping, though it ultimately doesn't really provide what I need.