In Canada condoms are considered medical devices and are regulated by Health Canada.
These regulation set down minimum standards that must be met when testing for strength and leakage by the local condom manufacturer or importer.
As long as you have a condom that meets these Canadian standards you will be fine regardless if it is thin or normal thickness.
A place I usually refer people to for condoms (they have a good selection and knowledge) is Ultra Love on Davie street. I spoke to them yesterday and they said that 85% of their market is selling thin or ultra thin condoms. They also said that they have very few complaints of condoms breaking.