This concept of yours is very interesting to me. It sounds like you have the potential for a wide range of settings for the roleplay. One moment you could be in the middle ages, then maybe a future setting, then the next could be the wild west. It could make the characters truly timeless as they would be the same in whatever time they take physical form to combat evil. Your concept also seems to ask what makes you you. The eternal souls of the good ones knowingly leave behind their memories of the past battles because they believe it would be a negative, but why is that negative? That is a question that could be asked by one of the pure souls. Your idea here has filled my head with ideas now. That is great.

By the way I will definitely join.