Situational Light Choices on V600: None, Nocturne (Purple, Blue, Pink), Solar (Orange, Yellow, Red), Passion (Pink, Red, Purple), Aqua (Green, Blue, Whitish), Elemental (Yellow, Whitish, Blue, Orange, Pinkish), Red, Yellow, Green, Sky Blue, Violet. Also, when charging or receiving messages, the phone displays a purplish-white light and when bluetooth is on it displays deep blue. And when you open the flip, the external screen just shows "AT&T Wireless" without any backlight and when you close it it goes back to normal and turns on the backlight for a short time.
My V600 says "Cingular" and I use T-Mobile. tee-hee. I got a leather case at Cingular too and it is pretty nice and should prevent the "self-scratching" issue. The case is a redesigned version of their previous V600 case...this one doesn't block the camera! Anyway, I would never cancel service with one carrier to join another just for a phone. To me it is too risky. Unless you are dissatisfied with your current provider's customer service, coverage, or rates, I don't think it is worth it. You might end up with a phone you like better...but if the service is not up to your standards...what good does it do?
^ Newer V600's don't have a scratching issue when it comes to the screen/buttons. But no matter what case you have, it will still scratch the outside.