Well i guess that provide a little bit of an advantage in low clear water, and they are a bit more sensitive than the foam ones.  They are between $6.99 and $7.99.  Are they worth it though???  Not in my opinion.  All it takes is one hook set when the fish isn't there and you more than likely have a broken piece of plastic on your line, with my luck the float usually comes flyin back and breaks on the rocks.  If you want a more durable float that still has the feel, I would suggest a balsa float.  I use them for steelhead and have found that they work great with a few slight mods.  But you get the most bang for your buck with foam dink floats.  They come in many lengths as well.  I use 4" ones for coho and spring and find that they sit just right in the water and they are pretty sensitive as well.  They also last a heck of a long time.  Get the straight through ones though, and use a toothpick to hold it in position.  That's my view on it anyways, and I have no problems with it.  Besides the foam ones are a buck!!!!!