Thanks for u-u-u on KvrAudio on creating a note merger! Version 1.1 now uses only one Polysynth instead of 12 so it has a much lower CPU use. The old version is still cool if for some reason you want a different synth for each note :)
It uses parallel resonant banks to separate fundamentals of each note of the 12-tone scale, and then fires notes with a replacer that has the octave modulated by two different sources. Includes a few controls to modify sound. Scale can be set my muting the individual replacers. It's otherwise pretty self-explanatory, just keep in mind that the effect is very sensitive to incoming signal so adjust "sensitivity" carefully. Best to automate it for the track the effect is on.