I have cast a few and like them for certain situations. Roll Casting, they are hard to beat. They also throw a nice dry fly with a light presentation in close. I think they are a little on the light side in close and on the heavy side out far due to the long taper that is characteristic of the TT line.
I am not familiar with the Cortland Sylk but am wanting to try it out. I have recently begun using RIO lines and like them alot. I like DT on rods I am not going to be casting long distances and WF lines on rods I plan on needing to shoot line or have a lot of line in the air.