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. "  

yes, The internal Osc doesn't go low enough. The 143-9 ss is great for the low and subtle shifts.

Very different from the crazy stuff it does. simple /easy mod,  recommended.

best,

phil