Realtime Synced Arp!
FN+Bank (Grid Rec off) > Scale Per Track
Fn+Scale > 2/16
Set your arp settings
Hold the first trig with a toothpick or whatever*.
Set your keyboard on autochannel.
Done.
That way you can play with your arp perfectly synced with the sequencer in realtime with external keyboard! 
Add random lfo on Note LEN to alternate chords / arp. (LEN = 0 = no arp)
*If you use it a lot : solder a switch! 