I've been thinking about building a mashup of the optical compressor in the link and a Blue Clipper.
http://www.diystompboxes.com/smfforum/index.php?topic=101118.0
The idea is to fine tune the LDR action so that the initial transient reduces the stage gain/clipping enough that hard & fast playing cleans up a bit, but chords ringing out have a nice and thick distortion. .
Think it'd work? Someone has to have done this because it seems too simple to just slap some clipping diodes on here and adjust the feedback resistors for the necessary gain. I'm gonna breadboard it this weekend.
Sounds like it would work.
I worked quite hard to make this compressor not clip too hard. However, this is a pretty common problem with compressors like this. By tweaking the 2 trimmers in the original design (increase 1k and/or increase 10k) it is possible to just get single notes/chords with a bit of space between them to clip.
I would suggest you put clipping diodes (e.g. LEDs) in the feedback loop of the first op-amp and then increase the gain (reduce the 5.6k resistor and/or replace this with a 10-25k 'distortion' pot.