I've worked for ladies across the country and P411 is known more in the south. Please know that I am a big P411 fan and love what Gina has built. It is worth it to be a member!
I have found that Date Check seems to cover a great deal of the country. I have spoken with the owner at length in the past and know some of the screening they provide. They do check employment on clients that have no references. They also keep a running list of references for gents so they don't have to keep up with it (just like P411). I do think, right now, that Date Check is more well known than P411 in states other than Texas.
In my mind, ladies can use both at no cost and that's always a good thing, right? Use these resources. For the guys, take the free trials offered by both services and see which one works best for you before you invest. It could be a win/win situation for everyone.
And that's my advice for the day!