according to steinberg, midi implementation has gone through a lot of enhancements with VST3 :
Quoting from steinberg website :
- No MIDI restriction for parameter value transfers
(...)This offers the possibility to e.g. modulate only a single note which itself is part of a chord.(...) - Multiple MIDI inputs/outputs
Plug-in can have more than only one MIDI input or one MIDI output at the same time.