Necky Zoar Sport
I fly cast from the yak and I don't use a drift sock. However, perhaps mostly because I don't use the sock, I limit fly casting from the yak to generally protected areas (in terms of current and waves).
For example, when I fish the big water of the Piscataqua River there is no time to mess around with fly lines. I hide behind structure (sitting with the yak in the lee of the current) and spin cast into the rips. It can be a little dangerous out there and I need to be able to cut my line if a huge fish pulls me into certain rips (tough to cut off a trophy but even tougher to cut loose a trophy and a fly line!).
My favorite spot to blind cast with flies is in the open Atlantic but on the shore side of a long rocky point that curves out into the Ocean. The point acts like a jetty to slow down my drift and knock down the waves. Then, when I see busting fish (fairly often this time of year) I paddle like hell over to them and fish. The trick for me when I stop to fish is to paddle backwards and away from the fish before the 1st cast. Otherwise I am still drifting into the fish when I strip and I furiously watch bass eat my fly but cannot connect!
I also fish in Hampton Harbor (NH) but in that case I usually beach the yak on a sandbar and fish from the bar. But when I blind cast from the yak in the harbor it is fun and very doable. I don't mind fishing in current but confused seas are a pain in the butt.
That is just my experience. And I like my SINK!