As a plugin :
- it can exchange (basic) midi messages with the host (no sysex, no timestamps, no filter... nothing)
- automation is now supported (well... kind of. don't ask for user friendliness ^^)
- any number of audio inputs and outputs
- smoother program transitions, especially for delays and reverbs plugins
- less cpu usage : unused plugins are not rendered
And the whole thing is more stable. Next : the rest...