i would suggest to avoid nano sinks as they are not as scratch resistant as granite sinks, since it is black in colour, any minor scratches will make it look ugly, regular hair line stainless steel would b better.

NANO = a coating like car nano coat, wont last forever.

Some nano sinks claim to have warranty but definitely no guarantee against scratches. Nano Sink price Vs Normal Sink price +- RM 80 only, not much hence many ppl might consider NANO.
Some brands sell NANO sink cheaper than regular steel sink, according to suppliers, they use lower grade steel then coat it hence it would not rust, so dont really need to use 304 grade steel. However, if u dont take care of the coating and damage the coating, it could rust.