If the higher self has a separate channel, does the self have to deal with conflicting messages from the deep subconscious on the one hand, and the higher self on the other? Is this dichotomy the true origin of the meme where an angel whispers in one ear, and a demon in the other?

This is an accurate description of everyday experience of the physical human being. It has a higher self whose primary function is to provide inspiration and guidance and reminders for staying on track and particularly, helping to orchestrate the life plan to meet the planned milestones and objectives that were agreed to in the light prior to the incarnation. In contrast, the deep subconscious, which is the bulk of the mind and has great power to influence the physical body, as well as communicating and obtaining information beyond the body itself, particularly from the akashic records, as well as a direct interplay with divine agents, becomes handicapped through the disconnect that is a true defect in the makeup, and this greatly reduces its utility and effectiveness as an adjunct to human experience and productivity. In many ways it becomes more a liability than an asset.