I bought a full sinking line on ebay, and cut it up into a few different length heads (10′-18′). Depending on what your doing, it can work really well. I use loop connections, and run about 20′ of floating line behind it, and then running line. I have a version of the orvis tips you found, and i found they are not long enough (ie. don’t get deep enough) for what i need to do. This kind of setup works really well for roll casting big, heavy streamers – you just have to make sure your are stripped all the way in to the heavier line or, like zach said, it won’t cast for anything.
Eric