There was a ton of usabe theory in there! Brought back many memories of my lessons. This article was one of the most concise expanations on chord substitution I have read.
Do you think you will be tackling the Augmented Fourth principle at all? Dennis (Sandoli) used to love using the Aug4 for key changes; I still use that theory now!!
Or how about the madness that is the Lydian Chromatic Theory to Tonal Organization? That book makes my eyes bleed! Lol (what does a steam ship have to do with music theory???)