... string relational operators all coerce their arguments into string, so that no explicit stringification is needed. But I may miss something.

The OP uses, and Athanasius's reply explicitly assumes, an equality operator, so I don't think you're missing anything. If you are, I'm missing it too, and I'd be very interested to learn what it is. (Update: Ok, here's something I missed.)

I agree with you that if you try to use numeric instead of string comparison, you're venturing out onto very thin ice indeed.

Update: I'm posting this reply again because the first post does not seem to appear in its intended parent thread. I can see the first version of this reply (update: this node) in the history of my posts in my personal node, but there is no link to any parent; it seems to be freely floating somewhere in cyberspace.