JP-8000 features only a virtual analog engine. V-Synth has almost the same engine, however, it's a semi-modular design in the architecture, with multi-model COSM processors instead of simple filters. But the most important part is the VariPhrase spectral sample processing which can do magic to any sound, from drum loops to human vocals. Go for the V-Synth, it has at least 10x more sound power than the JP-8000. The V-Synth can also route external audio into it's synth engine, and you can even switch between different processor types using the keyboard zones for some wild realtime processing of external audio.