The Tein EDFC only works on 2 models available for the S2K. Flex and SRC. Tein considers Flex to be one step up from their street suspension. The SRC is their top of the line model that has external resevoir, dampening and rebound adjustability, it also requires 2 EDFC units.

Since you seem to want cabin-dampening control, The Cusco E-Con is another option which only works with their top of the line Zero-2E coilovers.

I don't have any info on the Tanabe TEAS.

Personally I think Flex with EDFC is just JDM bling that won't better handling. Though If you're after handling I'm pretty sure in the right hands the SRC and Zero-2E would improve over the stock suspension, but as a previous poster mentioned with those you're spending ~$3k.

 

If you are looking to lower your car for aesthetics, which is what I did, and want to retain handling that is just as good as stock then the Tein Flex are fine IMO. I have them on my car and there is no way that the car handles worse then stock. They are definately better then the handling you will get with springs and stock shocks, which will definatley hurt your handling. I would recommend the Tein Flex, but I don't track my car so I can't justify spending 2-3k on coilovers for the street. I think the Tein's handle great on the street.