What's the potential spiritual benefit? For that matter, what's the potential physical benefit? And how can you avoid having this combination of music and aikido practice becoming at least in part about the music, thus taking away from the aikido practice?
You raise perfectly legitimate concerns to be added under the heading: why not to try and use music in the practice of Aikido.I feel each of these questions is best answered empirically which could be quite a project and I'm not suggesting you take this on yourself. However, your analysis of any empirical results would be most welcome as a skeptical approach is an important and essential part of the objective test of any hypothesis.