I think you will be disappointed with the color of the line. Spectra is next to impossible to dye, and the coloring you will see is in the wax coating. I know because I fly kites (The Kite Runner style kites) on fishing spectra (but 15lb). The color eventually rubs off in our hands.

Some other examples; Cuben fabric, composed of spectra fibers, is only white. Kelty used to make (still do?) a pack with 100% spectra fabric; it was all white.

Besides the color, spectra is slippery stuff. Great for sport kites (where the lines cross), but not good for tying knots.

I like the orange line over at Gossomer Gear for outdoor useage. VERY visable.