it' actually two resistor to mod the TS9. also, IIRC they're mainly altering the output buffer and don't have a really noticeable impact on sound.
personally, i'd go with a OD808. the input and output jacks on the ibanez tonelok series tend to get loose and the overall pedal construction leaves to be desired. if you'll be keeping the pedal always on and in a rack drawer it should be fine, though.