I don’t consider this backwards compatible. Every user of .numerator etc. would have to be changed. And what’s the point? So SageMath numbers can claim compatibility with PEP 3141? Even the stdlib’s decimal module doesn’t claim to be compatible with the numbers API. I really don’t see the point of making such a change. If you need to pass a SageMath number to some API that expects the numbers API you’ll just have to convert at the boundary.