I have a 3rd gen (flat type) TC 1Tb. I use it connected to my ISP modem and for TM backups for my iMac. I think it may be time to upgrade. I can't just use the Sky modem as it only allows a certain number of access if using the access list which I use, so I have to have another TC or Airport Extreme I think. So I have iPhone 6, iPad Air, Apple TV2/3, numerous other WiFI devices. Will the newer A1521 6th Gen Airport Extreme be good enough, and then I'll use a USB HDD connected to either the AE or direct to my iMac for TM backups? Will the range improve at all? I have an older direct plug in Airport express WiFi N (A1264), will this be "pulling" down my WiFi as its a slower speed? I use it to extend the WiFi? Or should I buy another TC? I see Apple UK selling refurb AE for £145, or I can get a 2nd hand from a local shop for £95, or buy new?