Hello Tim,
Good to see you here :) My apologies for responding so late to your post. Feel free to reach out dirctly to me when needed.
You are correct (I taught you well). I checked back on several email threads about this same topic internally to confirm that case restores from CW v61 to eDP v81 are supported. It's the appliance upgrade that requires incremental steps.
However, if you would like to confirm yourself as Daly suggested above I would recommend that you either yourself and/or have a support TSE validate this for you.
I can tell you that of late I helped a customer through an upgrade with case restores from CW v711 to eDP v81 with success.
If you find that this has answered your question please mark this post as resolved :)