It's also nice to be able to choose all your own gears on a cassette, and to have more usable gears without having to switch to a different chain ring. On my current bike build, I'm actually really considering just running the 8sp in the rear and not even running a double with FD in the front. The bike will look cleaner, be simpler, and be slightly lighter for what it's worth. I really only use 7 gears(which require a chain-ring shiftp) on my current set-up anyway, so....