Well the notes in the PRV would just behave like a key being hit on a controller. I could just program the notes in PRV so they cut off the previous note before things go wacky but at that point I might as well just program my own arpeggio and copy/paste it. I just want to hit a key, let it flop around the root chord for a while then at the appropriate spot hit another key to change the chord. There are programs like that in there but the cooler ones literally try to play what seems like a whole song. I guess that counts as song writing these days.