As I said there is no tried and true method of making digital negatives such as QTR for canon so I will not be buying a canon. I have neither the time or inclination to invent/make do/deal with inconsistencies and make my way in the dark. NOT BUYING A CANON. What I am willing to do is follow instructions, test according to those instructions, and get to the art of the matter quicker.
Optically enlarging the negatives? In 2020? Are you insane? Before you make any assumptions, I have done this, I was paid to do it, I was really good at it, and I would not even consider doing it now, assuming you can get the right materials and had what would amount to unlimited funds.
You and I have been around here for about the same amount of time. I have appreciated your knowledge and talent over the years. If you are ok with the P400 doing QTR I honestly feel pretty comfortable about it. Mind if I ask what refillable carts you use, and are they pigment inks?