MapMyRun.com - Pros: I can share my login credentials with someone, and we both can edit the map. A single location for a current map. A course can be marked as Private, so only I can see it; it can be marked "Accessible", so only people with the link can see it; then, when the course has been paid for, I can make it Public, so anyone can search and find it.
I can then download a GPX file to put on my Garmin Oregon GPS, and follow the course as I ride. No printed map necessary. I
Cons: Some people feel it is hard to work with, but that is the case with any program.
GoogleEarth: Cons: Must send KML files to anyone that wants to see the course. It does not show split locations, I believe. I believe you cannot make a path "Public", so it can be linked to in a Website. May be able to embed a link to the file in GoogleEarth, but that means someone must have installed GoogleEarth on their computer.
Pro: KML file can be placed in a shared DropBox folder, so anyone can get to a current version.
Just my bias.