I think that a router migration guide (replacing one router with another one, particularly a more powerful one) explaining the steps needed, would be useful.
Oh I really need to do this, also old key import is a feature that’s been sitting around undone for a while.
The real problem right now is that you can’t import the old key directly into the new router (for security reasons around the exit registration) what we need to do instead is take the old key and send all it’s funds to the new key.
I’ve done this a few times, like Justin said, by setting up the new router with a fresh setup and then transferring funds from the old key to the new key using Metamask. I think a guide for Metamask would be relevant here, like adding the xDai network as a custom network, importings keys, and general key security. However, this is going to change as soon as the new blockchain is live, so it’s not worth it at this point.