Yeah They are!!! Check out frozen cpu, or my local website pccasegear. They’re quite impressive.
Copper plates are rated at 300, so it’s probably still better to use a very very very thin layer of thermal past onto a copper shimm but from the heat spreader to the back of the case, you might still be able to improve things :-p
My tablet just left Hong Kong this morning, so it should rock up in the mail tomorrow. But I have a test on zener diodes in power supplies tomorrow afternoon so I might not get a video up about its temps until the weekend.