These would be ideal for use is low-power, small size HTPCs
Well... they *would* if AMD/ATI pulled their fucking thumbs out of their arses and released a driver with access to an HD decoding API. (that actually works)
NVIDIA released VDPAU donkeys ago and within WEEKS the Open Source community was able to use it.
More than a year after AMD release VAAPI and it still produces hundreds of rendering bugs - making it as useful as a chocolate teapot.
My HTPC running XBMC at home can decode a 1080p x264 MKV with the 1.8Ghz single core CPU bimbling along at about 5% utilisation. The heavy lifting is offloaded through the VDPAU API to a fanless GeForce 9400, which cost me about 30quid over a year ago.
I've yet to hear of anyone who's got hardware accelerated video decoding working reliably on ATI GFX hardware in Linux/BSD