RE: ...and what's the deal with nPULSE
These guys have got you on the right path with this synth, Greg. At first, like you, I thought the "n" in nPulse stood for "no". You have to rethink the interface as 12 programmable (albeit in a limited sense) individual analog synth modules. Ignore the presets unless you're going for an '80's vibe or hip-hop feel. Like AndyC says, though, paralleling some real drums (and/or Velocity) makes for some cool sounds.
You can even set it to the same port as your melody line, and use the key mapping to trigger a percussive burst on only select notes of a passage. The key feature here for me is the 5 assignable outputs: Disregard the module-type name, and tweak it by ear for a particular sound, then route that through it's own output & effects. For example, take some "Toms/Custom" and ring-modulate them, and send them through a delay line or the Spectral Transformer. Or increase the "Claps" repetions and feedback, and send it off to it's own deep phaser and output. Do something similar with the other modules, routing to different outs, and key-map appropriately. Now you have a whacked-out percussive line to blend in with your mix.
The nPulse is admittedly not a meat & potatoes-type of synth, and is limited in its programmable range. [BTW: When changing key-map or "clap" trigger settings, confirm with the Enter Key.] But once you change your mind-set of it as strictly "drums", some possiblities open up. This synth has a difficult time with carrying the entire drum/percussion line of a song, but it has its uses.