I think the main factor to consider is what the goal of the practice is. If the goal of the meditation is to induce an OBE, like you suggested, then Hemi-Sync is a great tool. I likewise use it for achieving OBEs and LDs. If the goal is to develop wholesome skills and qualities of mind and to eliminate the mind's defilements, such as the goal with Buddhist meditation practices, then using external aids is a disservice, as it induces a calm and tranquil mind without the need to develop the skills that are otherwise necessary to let go of attachments and dissolve hinderances of the mind to achieve that peaceful state.