A lot of manufacturers try to make their HTPC cases as small as possible, which is great if you're out to build an HTPC case that takes up minimal space and won't be used for anything beyond digital media playback. But did you give any consideration to gaming on your HTPC, or using it as a central media storage unit for all your other digital devices to stream from? With some careful attention given to component layout, it's not difficult to fit a full ATX system into a case that won't look horribly out of place on your component rack.
The GD08 follows in a long line of HTPC cases from Silverstone that aren't limited to mATX or ITX sized motherboards. The GD08 holds regular size PC components, right down to the ATX power supply and with a combined capacity of up to 12 hard drives the GD08 would make an excellent media server or home server case too!