In a lot of cases the domains with double plural are not buy ed. For example webmasterstalks.com was not buy ed because of that, but nobody thinks to this domain as webmaster's talks

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When I appraised my domain all told me about double plural and about reinterpretation of the name: a lot are thinking to webmaster stalks and not webmaster's talks

Anyway I think all depends on how promote your domain

Regards