Well, you kept it a lot
simpler than this thing! http://urekarm.tripod.com/synth/fuzzyballs.html
But I know what you mean. Swept filters have a tendency to invite more and more features. I'm sure somewhere out there is someone fiddling around with linear vs exponential sweeps, variable slope, auto-panned output, and any of a million things one can use.
Yesterday, I finally got an expression pedal set up to use with my Line 6 M5, and the unit allows for manipulation of up to 5 parameters at once via movement of a single expression pedal. Let me tell you (aklthough clearly I don't need to), it is VERY easy to get carried away with control features on a simple swept filter!
While I have filter afficionados' attention, have any of you ever worked with the Mike Biegel meisterstucke EHX Bi-Filter? http://www.ehx.com/products/bi-filter
Just curious as to what that's like.