Is this a recent kitchen installation? Could you ask cabinet maker to adjust the base units across to close the gaps up a bit more? Even if the splashback needs to be re caulked, better than trying to infil with stainless steel angles.

Okay, so as expected the matt suede surface is more expensive, not sure how much yet but when the builder says price on application, I can imagine it will be a fair bit more. Anyway, we'll see but something to take into consideration I guess... In the meantime, I was going through my idea books and found the photo below, which I kind of forgot about but is one of my absolute favourite kitchens... the point is just like the photo, we too will have a wall cabinet in matt black, the back of the island in matt black and oak floor boards in a natural/textured matt finish... so now I'm thinking maybe too many matt surfaces, interestingly they have gone with a polished stone top which I think is reflecting the light nicely... Our floors...

We have black pearl granite. Been in around 10 years and looks as good as the day it was installed. Easy to clean and doesn't seem to mark or stain. I would however not use black again as I think white would of looked much better. Granite being a natural product can't be matched up as easily down the track if you decide to add more benches and the like. Each batch can potentially be different.

When anything goes wrong it’s what is written on the paper that prevails. If the quotation you accepted says drop in and that is the supporting document then you’re out of luck. A total redo would be at your cost. You may be able to negotiate that they do it at a discount out of goodwill.