If you have the T8, the only real reason for grabbing the T8-S would be the ability to internally connect a hard drive (rather than USB) or dual boot Android/OpenELEC.
Oh, and DroidBOX Share -
Finally, if you've got a TV in a second room in your house, you can always slide the T8 there.
Re the hard drive and recording, only the same way as you could with a USB external hard drive. Live streams of TV channels can't normally be recorded, some of the other add-ons do allow it.