Can I say it depends?

Most of what I was saying about AUTOLOAD at Re (tilly) 4: Perl and Objects, how do you resolve the two? applies to custom imports as well. A custom import is like a very good sword without a hilt. It can cut really well, but you need to be very cautious before using it.

My rule of thumb is this. If my custom import could be done with Exporter, I don't use it. If it makes for a significantly improved interface and works very differently, then I will consider it. But if I won't actually use it unless I am going to make it a meme in the body of code that I am working on. It doesn't matter how nice each customized rule is, a million and one customized high-level interfaces is unmaintainable.

Or, to put it a different way, It is OK to be clever, but only one person should be being clever at a time.