Expensive HDMI cables are a big money spinning con right now. It's the latest thing you MUST have to go with your Plasma, the cable companies know this and are coining it in. It's a digital signal, that's 1's and 0's. As long as the cable is well built with decent connectors it will do the job. Longer runs, yes get a better cable, but over 1-3 mtrs, no difference. Same goes for optical cables.
Analogue signals ARE different though, better cable can make improvements.
And as for the Sony HDMI, can't see the problem with it myself on my Pioneer 428XD.