I've had black composite granite sinks and laundry tubs in two houses - the first for six years and this one for nearly 9 years. No problems at all. I love them. We are moving to a house that has s/steel and they will be replaced. I find the black granite so easy to clean, durable, and nice to look at. I don't know that I'd opt for white, given that I'm a lazy cleaner and I'd worry about discolouration.

BTW. I bought mine on eBay, quite cheaply. Not the expensive brand name ones. They've had plenty of hot water poured into them, both from a saucepan and when washing up - as we don't use the dishwasher much, and I like the dish water hotter than hot!