CU Go to Plus UME-ARN
I think that’s technically my first Diamond CU, prior to this it was due to equipment down-gauges.
On domestic and short haul I’d prefer to have the choice to accept/refuse an upgrade to Plus, since I’ve sacrificed an aisle seat without a neighbour in an exit row for a window seat and a neighbour.
Edit: actually the flight appears fully booked, but for a short hop I’d still take an aisle seat in the exit row over a seat in Plus.