HPSS could be generally interesting for instrumental records (percussion separation) as well as vocal records (plosive separation).
Especially in case of vocal records a higher quality algorithm is required, to reduce the propagation of audible artifacts.
Single pass (and real time) processing could be problematic, since the median filter kernel size tends to be large and requires samples from the "future".
Extract and transpose only the harmonic signal independently from the percussive signal.
TODO: