Usually a relatively expensive endorsement is necessary. 

The link is http://www.realestateinvestorswebsites.net/which I found searching for key words, and it was in this is a Bigger Pockets blog post...http://www.biggerpockets.com/blogs/640/blog_posts/27086-how-to-attract-leads-through-your-real-estate-investor-websiteIs this company legit, and Bigger Pockets endorsed?

The value speaks for itself if you investigate to any real extent. ...I have looked at the list of posts here on BP for both Doug Leedy and @David Dachtera, and it seems the vast majority of what they have posted is specifically things to endorse  / defend Renatus.  

Lastly, and this really applies to those with many locations, they work on an endorsement-basis.  

I'm surprised that you're so threatened by someone providing information regardless of whether or not you endorse the concepts or not. 

(listsource, send me a check for endorsement now....  :-) )

Does one have particular endorsements or enhancements or special coverages that the other lacks? 

To be clear I'm not endorsing frivolous nonsense, but unfortunately money talks and sometimes making companies pay is one of the few ways they'll listen (and stop ripping people off).

I'm just now exploring the same thing for MD and, though I will likely use a Title Co/Attorney for their documents and Trustee function, I plan to acquire one of the packages (about $50 from USLegalForms (not an endorsement, just what I'm planning)) so that I can see the language and understand the functions - as a minimum. 

They'll sometimes have brochures in the housing department office or flyers with available housing that they endorse.