not an SEOer, but I find quite ironic that any kind of hyphen / underscore matters because when things started …. if you had redwagons.com …. you were fine. now you’re telling me that red-wagons.com is better?
better, No. redwagons.com and red-wagons.com are essentially the same according to google.
Google treats the “-” as a “+ or &”. meaning it adds the 2 words together without a penalty.
If you look around the wen, you’ll see some sites like red–wagons.com doing well. I have no idea how may hyphens you can use before the site is penalized, but I’m sure google has thought of it.