I did play with HA using my air pad tablet but like a large screen when I'm doing a setup or attempting to debug.
A tablet is nice as they can be used as a touch control panel.
Both my low power PCs I got off ebay for under $50 and are mounted behind flat panel TVs.
My forum has a post on how I modified the HP to hold a larger SSD Drive.
I use wireless keyboard and mouse for both and run Netflix and a couple other streaming services + AHP, Alex10, PC Companion, and HA Bridge on the HP
The HP has slowed since adding Alex10 and Ha-Bridge but that's only during setups the drive is very full and streaming still works on this old PC.
The sound comes through the TV but only if set to aux input. This can be distracting if the security system triggers sound macros during a streaming session.
Both only have 4 gigs of mem and that is their max. A newer low power PC with more mem and faster CPU would perform better for streaming.