As an alternative, take a look at the new "Asso" sinking mainline.
I'm using it at the moment and am very impressed with it.
I'm on the 16lb version as I prefer 0.35mm diameter and it's doing everything right so far. Knots well, casts well, sinks well, (obviously!), and hangs nice and limply through the rings.
http://www.assouk.co.uk/Asso-products-Sinking-Mainline-Carp-Mainline-fishing-line.shtml