Keep it simple and real time, except for long term trends on more complex questions or issues. Sonification of HRV is my target. Got interested before cardiac ablation resolved atrial fibrillation and continue exploring with a simple Polar monitor and attachments based upon the Polar Heart Rate Module - RMCM01.
SuperCollider programming is still developing, but my real-time heart beat in my ears turned out to be a terrific feedback instrument. Never much for exercise groups or formal equipment, going with the flow of the tick of my heartbeat lets me explore movement in new ways. Walking down the street now has dance elements woven into the internal visualization of body and mind state. Bliss is remarkably easy to recognize and propagate - shifts in attention are markers for a drifting state that is absorbing on many levels. Having this tool allows for lots of tiny experiments with interesing results.