The odds of getting slate to match your tops are very slim. I don't think slate is good kitchen sink material. What about the corners? How will you get and keep them clean?

Are you belfastbound as in Belfast Maine? Slate never gets a very good reaction here on GW, but it is very popular where I live which is Maine.
Several of my friends have slate counters and slate sinks, Monson Slate, Sheldon Slate, etc. They are very beautiful and I havent heard of any problems, and I cook, eat, wash dishes frequently at one of them.
I would give Morningstar Stone in Topsham a call and see if they have an opinion, they are very helpful.

Hi local eater, Yes we are building in Belfast Maine.

Thanks for the Topsham tip. I am in love with the green sheldon slate though I have not been able to pair it with a granite slab I like and I have been tramping all over Boston to Maine so may have fabricator make a granite sink.

Had not considered gunk stuck in a square corner of sink, but thanks to your experience, I am not going to worry about. That is what toothpicks are for :)