I too also prefer using a TV as a computer monitor instead of a computer monitor monitor.
At this point it's a no-brainer for me. My big box is my 'everything server', and does 'brute force' work. So using the everything server directly as the media PC eliminated a screen. Productive work then gets done on a laptop, with the brute force bits farmed out to the server. The other thing is that with Linux I can use SSH and NFS mounts to transparently use the server box from most of my devices.
The guest user account automatically logs into a media desktop, so anybody can switch the HDMI input and use the wireless keyboard and mouse to play any media I have (read only), or to surf the web on the big screen. That box has a fully mirrored RAID, and regular backups, so it really is a workhorse for me...