Has anyone else done this? Can anyone speak from experience? Is it a bad idea for any specific, technical reasons?
I can imagine they get automatically blocked / filtered by some corporate content filters, VPNs, firewalls. But I feel I could have a few secondary domains to cover access in those scenarios.
The name plays on the name/domain hack of “fill in the blank” ie: something.xxx
Most people will assume you mean something.xxx.com, or that it's a dev url and you haven't launched yet.
If they are brave enough or native enough to Google your name, whether or not your site ranks, they will be presented with pornography one way or the other.
Your url may or may not get automatically turned into a hyperlink in their email and chat clients.
As you said, your emails will not make it through corporate filters, your site will be blocked, etc.
You might be able to work around technical issues with secondary domains, but from a business perspective you will vastly limit the pool of clients willing to give you a shot.
Besides xyz being ‘clean’, I don’t usually associate xxx with fill-in-the-blank. Only moonshine and pornography.