For what its worth, I've never had a problem with cutting a Riffe float line. However, I will admit that I generally dive from a boat so its not being dragged over the rocks, but I have a lot of friends who do drag them over the rocks and don't recall any of them mentioning problems.
For my kind of diving, the biggest danger to a float line is being run over by a boat. Props cut them very easily, no matter what they are made of. For that reason, I would not recommend going with the blue color. It may seem sexy to have a blue line to match the blue water, but it sure makes it hard for the boat operator to see it. I love my orange line from Aimrite because its so easy to see. Unfortunately, I don't think they make them any more.
But getting back to where we came in- twisted poly lines are a lot cheaper to replace if they get run over.