So you're blending between a high pass and a low pass in filtration stage it looks like to me, did you experiment with a band pass at all, or did the current design yield more extreme frequency sweep?
I count 8 opamp, just out of curiosity did you use a couple of quads? I'm not very savvy at circuit design and I know sometimes you get better results splitting it up into a couple doubles for close noise etc.. though that all seems to be handled by the microprocessor.
Every time I dream of my ultimate delay I always lust after a "repeats only" FX loop - which is pretty easy to do with an added TL072, but do you think with a design like yours it would be best handled by the microprocessor? Not sure if this is even the best place to ask these questions, but since we're all here celebrating your devices why not?