I am a member. But my membership to the national organization that you mention came free with my $25 annual dues to my local TulsaModern Quilt guild. I do get emails from them with links to some free online quilting short classes (generally one hour long) that sound interesting but have not yet logged into one. Otherwise I think the biggest benefit relates to the huge QuiltCon show that is one of the biggest annual quilt shows. Being a MQG member gets you discounted entrance and class fees and first chance at the classes there that fill up in a matter of hours after registration begins. If you don't plan on going to QuiltCon, I am not sure there is much benefit if you don't have a local modern guild.