Me too. The synth effect on the LD's is the only effect on those amps that I really liked. You had to play with them tiger a usable sound, but it was fun.
Just get the Electro Harmonix Micro Synth. You can get so many tones...from that Gap Band Sound on 'Burn Rubber' to the bass synth sound on 'Jamaica Funk'or 'Let's Groove'.There is really no need for any other synth pedal