The advantages of using the SP plugin are felt most by users who want to multi-track record or take advantage of Ableton’s looping effects. Here’s a short list of things the plugin enables from the 1.7 blog post:
It does make controlling knobs/faders in Ableton more complicated, as you either have to route the MIDI out and back in via a virtual bus, or use a Max for Live device from the building tools pack. The virtual bus method is complicated by the fact that Ableton strips MIDI channel information coming out of plugins.
The Max Api CtrlMIDIcc.amxd is the device from the building tools Max for Live pack makes it possible to send CCs from the Sensory Percussion plugin to Ableton’s UI.