For users to make a more smooth transition to the new Edge, there should be a process to copy/migrate the state of the old Edge over when the new Edge is first run. In addition to favorites, any open tabs and Windows, along with their forward/back history, should be migrated/preserved. Also, the Set Aside Tabs should also be carried over. Users should also be notified about any extensions they may want to install on the new browser if those are not carried over automatically.
For many users it will be very difficult to move from the old Edge if they have many tabs/windows that they keep open/active for extended periods if those are not easily migrated over. Same goes for Set Aside Tabs. Many have come to heavily utilize the Set Aside Tabs feature also and if those are not carried over it would also cause issues or us.