Usually have good success on the exchange. when we can't go we usually put the pair up next to each other so I think they are more attractive than single seats however I have had a couple on the exchange that did not sell. Especially midweek games.
Good work with the increase to 10 as I may not make as many games this season due to work and family commitments but I think a bit more needs to be done if they want to reduce empty seats further. We live outside of Manchester so passing the card onto someone else isn't feasible. Also the issues of being responsible for whoever happens to be in your seat worry me about selling it privately. It would be good if there was a way to exchange your ticket to an eticket so you could either sell it privately or gift it to someone and therefore remove your responsibility for their behaviour if they do happen to cause trouble. Or have an internal club system where if it doesn't sell x amount of hours before the game you can chose to either have your card re-activated as it does currently or donate it to randomly chosen local supporters who maybe can't afford to attend?
(Although the cynical view would be that this does give the club the option to pretend to donate it and then sell it on anyway to make money)