I think they are fine for
SEO purposes , But when it comes to Branding .... Nah
- 1) Traffic can possibly bleed off to the non-hyphenated versions as stated already.
- 2) Try to imagine advertising a hyphenated domain/website on a Radio station or even on TV ... On the radio you'll end up with an announcer saying "Something Dash Something .com" -or- They'll leave it out altogether .... - On the TV , potential visitors only have a few moments to let the domain sink in, And may forget the hyphens when they try and visit it later.
They're fine for
SEO/Traffic , But a possible disaster for serious Development or Branding.