I was at the dealer over the weekend getting a new air filter and it turns out the new wiper blade assembly was only $13 -- twice as much as an insert but worth $6 extra to avoid fiddling around in the cold and to get nice new black plastic on at least part of the wiper arm
Getting the old one off took a minute. You have to flip the blade to almost 90 degrees to the main arm, which means the end is jammed up against the window but gives just enough room to unclip it.
Thanks for posting the insert replacement diagrams.