I personally believe that the post is for sight and bouyancy - I don't think the fish see the post as much as on a paradun fly.
I have been tying my own klinks with chartruese, orange and pink CDC posts and this does not seem to have affected the success of the patterm - meaning that I do not believe that it has put the fish off but is certainly better for my eyesight!
http://www.flytyingboutique.com/stor...136&category=6
I do not think that Antron posts float very well so always use Aero Dry Wing if I want a virtually unsinkable klink for rough water. I do tie in the hackle with the best side down to give a tulip effect to help the pattern swim low in the water.
Kind regards