I hadn't heard of Slice until this, and I watched the video. Have you used one? It was compelling until the part of manually adding content via USB. I assume with network connectivity that media could be loaded like that instead, but the video didn't make it clear, and it seems pretty lame to have to plug it in to load up.

No, I've not used one. I believe it's designed to be primarily an offline media player.

As the Pi sucks at I/O, the idea is that you mount the HDD directly over USB and transfer files to it from a regular computer. Network transfers would be very slow due to the Pi bottleneck.

You can load media via the Ethernet connection but it is limited by the performance of the Ethernet interface (10/100).

We offer the USB loading method as a faster way especially for the first time when you want to load up your entire catalogue!