Yes. I've played with those for a different project quite recently.

What I discovered was that work really well if they can keep their data structures in L1 cache.

But using them from Perl code inevitably means using perl's hashes (all of Perl's namespaces (packages) are based around hashes), and they by their very nature exhibit very poor locality of reference and thus mess with the caches, with the result that the performance of Judy arrays drops away significantly.

Also, they are as you mention, horribly complicated beasts which is fine until something goes wrong, and then you're up Sneak Creek without a paddle.