I am actually involved, right now, with securing a couple .xxx domains for a client. Although not an adult product, the client wants to protect their product name from being associated with adult content.
For the record, my client is happy to pay the large (compared to normal domain registrations) fee to keep their .xxx from resolving.
For the record, my client is happy to pay the large (compared to normal domain registrations) fee to keep their .xxx from resolving.