But what are the odds that you have a .com that generates appreciable direct navigation? Those are scooped up by domainers and ISPs.
If your .com does not generate direct navigation then I'd say a three word domain is more readable if it has hyphens.
It will actually look better in print (cards, ads, etc.)
It's a fair bit easier for soemone to communicate the url to other folks verbally, not at all unimportant if you hope for users to be telling their family and friends about what a great site you have.
I don't know about non-hyphenated looking better in print, but if you want to be able to sell your domain or site, then non-hyphenated domains have a better rap.
I preferred to register science-education.tld over scienceeducation.tld, with the double-e. IMO hyphenated domains are undervalued because of direct navigation.