I have had a canon MP630, they do print on ty watershield but they leave roller marks on the printed finish. I have used verbatim waterproof discs as well the same result but no where near as bad as the ty’s. I have tried a canon ip 4600 and a epson rx685. the same result.
The problem is these printers pull in the disc trays with the use of the rollers, the watershields are thicker than ordinary printable cd/dvd so more pressure is put on the disc causing the roller marks. These printers are not designed for watershield discs. I have read in certain places that the older canon ip4200 does print on watershields and one of the epson’s maybe 320 or 300, older versions. Never buy an Epson though, if it goes wrong they offer you a refurbished model. Honestly there after sales service is the worst i have come across, but it’s up to you.