Have you done the mod  I'm not sure if I understand exactly gets improved.  I see " It enables frequency shifting even below 50 Hz generating e.g. these mellow beat sounds with a few Hz frequency shifting only. "  
But I'm not sure if that mean "wider range of shifting... (i.e you can shift as low as 50 Hz)" or "more precise shifting... (ie you can make very small shifts with as little as 50 Hz change)" or both or something else.


In the ideal sense I'd like to make the mod in a way that:
- preserves the option to use the frequency shifter and LFO/OSC as stand alone as well....either via switch, patchable Breakout panel, or jumpered connection.  I think any of those options can be done with only a minimal amount of work. 

- potentially allow me to have multiple carrier wave options e.g. I could use A-143-9 and/or other suitable quadrature LFO/VCOs interchangeably.  It may require a bit of research on my end to determine the best carrier waves for the job.