I've, like most of us, never played a real RSF Kobol Expander (the 19" rack synth this is based on), but it surely sounds wonderful. Warm, fat, raw and when patched up, extremely vivid and weird/wild.
With the additional rack ears, I've mounted it with my other semi-modulars. At the moment I'm trying to figure out how to make space for yet another Kobol Expander. The two of them will surely make a great team, in unison or duo mode, patched in between the both units.
A must-buy if you want something extraordinary.