Ps. Re: Sigma and focusing -- this seems to be the nut that needs to be cracked: http://briansmith.com/sigma-mc-11-smart-adapter/
Hi Lane -- I'm in the same boat and also searching out more information. Obviously the new GMaster Sony series is out. It's expensive and very few reviews have come back yet for video use. I'm also interested in the Sigma -- especially because their new adapter supposedly passes everything through. I need to have fast, smooth focus. So no answers here but wanted to say you're not alone in that boat.