Hello, I'm about to purchase an imac 21" . I decided I wanted the fusion drive version of the Usd 1300 iris pro model ( about Usd 2100 in my country) . But now I'm in doubt between getting the usd 1500 imac model with the GeForce ( without FD) and the Fusion Drive 1300 iris pro model ( both 2100 here). As I want performance speed, can I buy an external ssd and make it work as good as the fusion drive or internal ssd works? should I get the GeForce model or iris pro is good enough? I don't need the greatest machine, but want it to last for years. Sorry for my English and thanks for the advices.