PNG,
The 9C is far more capable than the 8U in terms of mixing capability. The switch assignability is worth any difference in price. Futaba's site has a comparison page pitting the 8U versus the 9C, and it would be worth checking out. With all the people raving about the 9C, it would be worth looking into more than a 50 dollar difference.

Also, the servo display might sound like fluff but it is useful in that you can set up your programming without having to set up the aircraft in front of you. I actually used this feature when programming a complex blimp.