Here is what I use it for: 
-if you run a simple sequenced VCO through the Muxlicer, you can chop it up, create variations in the pattern, morph the wavetable by combining other VCOs in the per-step inputs. That's fun. Especially cos the sliders allow you to easily create variations playing live. 
-sometimes I use it as a simple, but randomizable step sequencer. 
-It is also great as a gate sequencer, opening and closing VCAs, creating crazy patterns. 
-all of the above, while triggering drums through Muxlicer's gates, EOC, and surprisingly useful clock output. 
 
Generally is great for live use, very versatile, and mostly tons of fun. I thought that together with the Percall it might be redundant. Well, I was wrong, they're a killer combo for creating drum patterns + melodies. 
If you love sliders too, you cannot go wrong.