It would have to be cut because most backsplash spaces under cabinets are between 16" - 20". I prefer 18", which still allows us short people to reach a few shelves in the cabinets above!

I don't mind a large tile, although it is rarely used, but the problem I have is with the tile pattern you picked. The marble-look porcelains are usually used in bathrooms, so that is the vibe you will give in your kitchen!

When you say your counter top is "white quartz" what do you mean? Plain white or another marble-look product? You really don't want two marble-looks, in different materials, next to each other.

Good points. I was also worried if it would give bathroom vibes.. thank you