FIrst I am hearing about PHB +1 myself. I have never played Adventure League myself, but their rules for things like downtime, and character death seemed to fit here pretty well.
If this PHB +! means you may use only one other book, than I don't believe that is what we are doing here. We are using anything that is Core Rules for characters A-c, and anything third party or designed by a player - like the monk alternate path from Greenmtn.
I probably should update character gene as new stuff comes out.