I set out a few years ago to work only ABO. When I made this change it was very hard to learn because it required a different skill set. After a year I have a new set of skills and never gave copper a second thought. But here is where it gets weird...I went to went tam's house to teach him some knapping. Without thinking I started instructing him with copper because it was the tool set he had. Funny thing when i started pressure flaking I said "for some reason it seems easier doing it ABO" .....now that is a funny mind shift. Clearly when I was using copper all the time it was easier ...Funny stuff.