So why on earth does anyone use HDMI (except for the reason that it's included in almost all consumer products). SDI is clearly a far better solution. Reminds me of the VHS v Betamax or HD-DVD v Blu Ray wars. The better technology is pushed to the sidelines merely because of popularity and marketing.
HDMI has a return path and is cheaper to implement since the transceiver rates are lower (though the aggregate is higher), but it has also been ahead of the curve in aggregate bandwidth with the SDI standards still not final on 6Gbit/s or 12Gbits/s while HDMI has had those rates for 5 and 2 years now. Or consider that SDI has no copy protection or encryption on it while HDMI "asserts" "rights"