So, you're saying the one issued by the bank is analogous to buying paper gold, where the issuer of the paper SAYS it has sufficient gold to back up all the paper, but no one actually knows if that is true. PLUS, there are some ridiculous extra tax twists due to it being a French company.
Knowing how two different brokers treat a British stock we hold (in two accounts) entirely differently, I agree the tax issues might open a Pandora's box of complications. Still, look at the chart....