Hi guys, would like ask for your advice on my plan to upgrade my iMac 21" mid 2011 (8gb ram, 500gb hdd) to iMac 27" late 2014 5K (8gb ram, 1tb fusion drive). this used iMac 27" late 2014 will cost me around ~1700USD include apple care until Nov 2017. my iMac 21" mid 2011 can give me around ~500USD if I sell it I believe. So the net money that I need to fork out is around 1200USD. Is this a worth an upgrade? My only concern is 5K imac cannot be used as external monitor. >.< do u think the current spec can last for 5-6 years? I don't do professional video/photo editing and high end graphic gaming (I know then why I want to buy 5K iMac right? hahaha). I am interested to buy this 5K iMac because of the reasonable or cheap price. Appreciate ur feedback and comment!