Soldato
supported linux devices.
http://www.linuxtv.org/wiki/index.php/Hardware_Device_Information
if you want hidef you'll need dvb-s2 and dvb-t2 devices.
saving the streams takes very little cpu, playing them back (offset by vaapi or vdpau hardware decoding) or transcoding does.
i have a small ION2 dual core atom machine with a 1TB 2.5" drive, running ubuntu precise, mythbackend and xbmc as the frontend.
it's powerful enough to record multiple streams and playback but not transcoding.
That sounds really cool.. Are the usb2 one not worth the bother then ?
I also take it that when you talk about transcoding that you're trying to rebroadcast the stream to your LAN devices similar to a uPnP/DLNA server (good idea)