looks great!  thanks.  

just noticed that the highpass output is too hot.  instead of multiplying the distortion outputs by [1, -2, 1, 0, 0 ] , you need to multiply by [0.5, -1, 0.5, 0, 0], then you get the same amplitude for the highpass as the other modes.

I'm gonna see what it sounds like to morph between filter modes with a line~ sweep.  Hopefully it will work somewhat.

Matt