I'm not sure about this. It's one more task for certifiers, but more to the point, it changes the neat 2 letter-5 digit-2/3 letter system already in place. Isn't it possible for the record keeping folks to download a complete course list, do a sort on the Drop and Separation columns, and cull out those that don't make the Record Eligible cut?
I also worry that having "NE" appended to a course listing might become a Scarlet Letter(s) to runners who might feel "this course isn't fast" when they see that.