Ahh ups, hehe, the name Schroeder made me asume it was reverb.
What would a allpass schroeder version be used for, besides reverbs?
I just looked through the link you posted. I now see what you mean. Argh I am not good a schematics, so I always look many places before I find an explanation that I get...... But I still think the schroeder all pass filter can be patched up pretty easily. To me it looks like an AP filter with modulation and feedback/feedforward.
ANyway, think I need to try making one now. It is a bit different that the filters I used for Schroeder reverbs.