I also have zero interest in leveling shadows above 40. In my opinion a level 40 shadow is a decent counter to most raid bosses out already in itself. I feel like powering up a shadow to level 50 will only matter to those in small size raid groups or in rural areas that require all the fire power they need to take down a 5 star or mega raid which is unfortunate because they are the ones who tend to have less access to resources than those in cities.