I have been professionally cleaning homes for many period's in my adult life. Right now I'm a teacher out of work and back to cleaning. It's not a bad job, but I do have to be careful as to not damage granite, marble etc. After doing some research I learned that both granite and marble are a natural derivative from limestone. Vinigar is a no no, windex or anything with alcohol is another no no. These chemicals will actually break down the stone in time. Yes, the company's do put a sealer on the granite or marble but it does wear thin in time. I personally would not get a sink that is a granite composite because the seal won't last very long and I don't think it would hold up very long. This is of course true if your kitchen is used. Some people have the most beautiful kitchen's and rarely cook in them. If this is the case a granite composite would be fine. Barkeeper's friend or soft scrub should clean the sink you have just fine. Grace