Here's an interesting observation. I have several celebrity sites and my oldest ones are 8 and 9 years old respectively. The old sites have dashes in the domain because the non-dashed domains were taken long ago. Both are doing fine in the serps. The key word searches for search engines reveals FirstName LastName searches. I've recently bought some newer up and coming celebs and was able to get the names without the dash which I find so annoying. What I've found is that I rank higher for the FirstnameLastname strung together for both sites than the keywords separate. I don't have the firstnamelastname strung together anywhere on the pages nor with external offsite anchor text. So... from my findings, the dash does help for SE ranking but probably not for human direct traffic which is usually lower quality in regards to advertising.