I've seen it in live code, and it took a long time to figure out that was the problem. It's not worth taking the chance until Perl 5.10 is commonly used, in my opinion.

I guess that's one approach. However, if it was me, and I was discovering this construct in a lot of code, then I'd write a test to go scan for it and warn me if it crept into the codebase - and train the developers to avoid the broken construct.