First, if you are going to have a semi-permanent or permanent layout, then you should use some form of roadbed for your track. As already pointed out, it will make it look much more real and give your ballasting something to form to.
In my return to MR, I decided to give the WS foam roadbed a try. I am very happy that I did. It is very easy to form any large or small radius that you need and is very easy to lay down. Some use liquid nails, but I prefer laying down a couple of beads of undiluted white or yellow glue...let get tacky...lay the foam on top pinning the curves down, and give it a few hours before laying the track down.
I will say that there probably isn't that much difference in the foam roadbed and the cork other than the ease of installation and personal preference. The argument about which one is best to mute noise is nonsense. Once the roadbed is covered with ballast and glued, both become a hard shell that only softens the sound some and about equally. Most of the sound on a layout is transmitted through the benchwork and hard scenery.