I really like alts. They can add a new spin on the character as well as show character growth and change in a way that's reflected in the gameplay. As for what id do differently, I know it's a fucking PIPE DREAM, but I think it would be cool if unlocking an alter was less a pull thing and was more about completing a challenge. Amiya had something like this and I think it's a neat way to further incorporate the story of a character into the actual gameplay.