anton,
first off, why not use an actual d*mble soundclip as your reference? right now you're trying make a pedal that copies a pedal that copies a d*mble amp. (if you get what i mean. hehe!)
second, and more importantly, i think one of the "failures" of most pedals attempting to cop the d*mble sound is that they can get close to the sound, but not to the "feel" of a d*mble. that said, who among us has actually tried a dumble anyway to make the proper comparision, no? regardless, many have described the feel of an ODS as rather immediate, and can go from clean to overdriven simply by changing picking attack. i think if this aspect can be captured, then you will definitely be on to something.
lastly, one oft overlooked aspect is the clean sound of the dumble which in a pedal format is quite impossible to incorporate (since when you bypass the pedal, the clean you get is that of the amp used). i suppose this one can be tackled in terms of the 2nd matter i raised, wherein the clean portion (of the clean to mean via picking attack aspect) will have the characteristic d*mble clean sound when the pedal is on. again, if this is achievable, it would be an improvement over many d*mble-type pedals.
my two cents.
i hope this isn't confusing. it's late and my mind is cloudy.
cheers.