tl;dr:“Whenever doing a big migration from system to system2, front-load as much work as possible into building migration scaffolding to system2. That way you can migrate to system2 as seamlessly as possible, without a huge manual migration effort, one piece of functionality at a time. Then you can undo the scaffolding from system. This “Strangler Fig Pattern” is the key to making large migrations successful without putting the burden on your customers.”