Chris, I cannot say enough how awesome a touch this is. From little funny quips in the rule book, to being able to fit sleeved cards, gamers notice this, and it means a lot. Well done sir.
What size sleeves are those in the picture? The only ones I could find in a local shop that the cards could fit into were penny sleeves. As a result the cards take half the amount of room as those in the picture, so the cardboard insert does not hold them still.