Hello! I am thinking of purchasing a refurbished 24 inch Imac from the Apple Store (when it becomes available). I wear glasses and I think a screen size of 24 inches or larger would better suit my needs. Could anyone please tell me the differences between the 24 and the 27 inch screen (I know that the 27 inch screen has led-backlight), in terms of brightness and contrast? I would appreciate any feedback/info regarding the differences in brightness and contrast between the 24 and 27 inch model and if it is not too much of a difference, I would prefer to go with the 24 inch model. Thanks in advance for your help.