The Midi FX are pretty cool, I find the Chord Analyzer a bit sluggish at times in playing from the transport, but fine in real time
The midi Echo is really flexible and allows this to note offset the each delay and choose chromatic or diatonic scales, you can swing them too. nice for creating runs. If you set the number of echoes to 3 and the delay to zero in milliseconds, the notes occur at once, creating a 4 note block chord from one note.
If you then add the Chord analyzer after the Echo, it will show you the notes created, the chords it has made.
Transpose is pretty cool too, you can run you midi performance through it and see how it sounds in different keys or in different modes. Change you melody and chords from C Ionian to C Dorian for example.
Put in sequence, of Echo>Transpose>Analyzer will allow you to create block chords from one note, then fix it to a key, changing voice shapes as a result, then see what these chords are as a result. Seeing what interesting chord progression you make by accident. Playing into this is pretty fun (I use a windcontroller which is monophonic player only, so I can get pretty expressive chords from one note). After you have something, you can see what make minor changes to this the midi FX chain and stumble across interesting progressions, Open the voicing by playing with the pitch offset in Echo, adding more note extensions, changing the keys and modes in Transpose.
I've not used to Arpegiator that much, it's pretty cool though and nicely laid out. Add this to the end of the MIDi FX chain and from one notes on you keyboard you are creating interesting arpegiated patterns of interesting chords voicings and progression.
The midi event filter can help out too, when you get into difficulties. My windcontroller send pitchbend very easily, and when playing keys, it sounds wrong to modulate the pitch. Most time I can turn pitch modulation off in the synth and continue sending pitch bend, but when I can't, this comes to the recue.
I don't use the quantize, but someone recently asked about how to make straight drum hits sound more natural. I think this would be another good tool for that.
It' a shame it's not been added too. A chord device, where instead of haphazardly like above, I can define the notes that will result when I play one note from the keyboard. And a midi voice splitter to allow notes to be output to different midi channels. Through ranges or intelligently assigning notes from a chord to different midi channels, based on their order. So bottom notes go to 1, the next note up to 2, and the next to 3, and so on. So a four note chord could be assigned to cello, Viola, Violins one and two, or baritone, Trombone, alto and trumpt