That is the option involving minimal change. That way, the ridings would remain the same. The voting ballot would be exactly the same as the one that already exists. All that would change would be the way the ballot paper is marked.
In addition, it would take longer for the results to be known. You may have heard about the Australian election. I believe you have spoken to the authorities. I was travelling at the time, but I felt that it took a very long time for the results to be known. So it would take a bit longer.