Thanks for the comments. As for Cyclone Slash, it will generate more threat overall than Slash when used, but this is because mainly because it costs less Focus (2 to Slash's 3). Thus, Cyclone Slash generates more threat per second if used as the lower amount of Focus gives you more Cyclone Slashes. When used an equal number of times, though, it generates significantly less threat even being high threat as it does such little damage.
In the thread you linked, another poster, Methoxa, replied showing that one use of Cyclone Slash generated 2119 threat while Slash generated 2743. Since we want to maximize threat initially in the opener, Slash will give you more aggro in the short time you need to hold aggro.
I could be wrong but isn't the focus cost of cyclone slash 3 focus and it generates 30 percent threat from soresu stance?
In Shien Stance as a Vigi guardian i lose a net 2 focus from using cyclone slash, and shien stance refunds 1 focus making it mean that it SHOULD lose 3 focus. Not positive though.