One of the "bugs" of Windows 8 is that the user is not allowed to set different zoom levels on extended monitors. What this means to us is that if we have our SP set at 1920 x 1080 and 150% zoom, then our external monitor will also be 150% zoom. With a 23 inch monitor that means text will be so big it's almost funny. One workaround for this is to set your SP at 1600 x 900 and 125% zoom. This is going to give you pretty much the exact same real estate on your SP as 1920 x 1080 x 150 but more reasonably sized fonts on your extended monitor since the zoom is only 125%. Additionally this will also give you an extra row of tiles in Modern UI (don't ask me why, it just does). So does image quality suffer on the SP at 1600 x 900? YMMV but I personally cannot tell a difference.