I have both as well, but I find myself throwing the Fusion almost exclusively. The Soul has been a little big over/under for me, but I'm currently bowling on mostly wood THS. I slaughtered brackets in a one tournament where I had enough volume to use the Soul, so at least it's paid for
I've never considered buying two of the same ball, but right now, I don't see why I wouldn't get another Fusion.
I think I have not had much luck with asyms, so that may be an issue as well.