The only downside I can think of is that the backsplash can serve as the design element which pulls other things together. It can also serve as your 'pop' or your 'wow factor'.

I've given a little thought to this too. Sometimes, I think it is a bit too humdrum, expensive, and a missed opportuity for "pop" as westerchermom mentioned, but other times I like it. Nethertheless, I decided agst based mostly on too much consistency. However, if this isn't a problem for your design........

I agree with other posters. Yawwwwwn. If you're going to do that, save the money and do a 4" backsplash with the slabs. You'll still get the look, while preserving some drywall for paint, which the space will need for some relief.

Counter ennui? J'ai triste de mon cÂur. You have to imagine it said by Pepe Le Pew. Leetle keeses

Need to check your faucet clearance and perhaps other appliances that may have clearance issues - like a range that ends up sticking out 1/2" when it was supposed to be flush.

I also considered 7 or 8" backsplashes that I saw in some pictures. Enough for a statement, but left some room for paint

Here's a picture of one of my showroom displays with a full Caesarstone backsplash. This is Pacific Reflections, which they recently (unfortunately) discontinued! It's gorgeous!