Lesson learned
After moving to 'refill-type' cartridges (purchased from one of the main NZ businesses in that field), but experiencing more than one cartridge failure and/or short ink life over the past couple of years, I have gone back to buying the genuine Canon ones. Obviously no scientific comparative study, but it does give me peace of mind that I can rely on getting a decent photo print when I need it. Also, as always, PBT's service was prompt, and their ink cartridge pricing was the best of the suppliers I checked at the time of looking to make the purchase (of several cartridges).