I think it should be something all dog owners are aware of, regardless of if they own a giant or large breed. My Toller had a gastric torsion over Easter, thankfully he made a full recovery, but Tollers are certainly not classed as a large breed. I'd always assumed any dog can get it which is why I spotted it so quickly, but it also meant he was extremely unlucky to get it as I've always taken precautions against it e.g. not feeding before exercise etc.
Since his torsion I've also heard of border collies, and even a cocker spaniel getting it. So although very rare, any dog of any breed could potentially get it - it doesn't hurt to be aware of it regardless of your breed.
I just wanted to make a point that it can happen to any breed, large or not, deep chested or not. It's just that it's a subject that is pretty close to my heart at the moment - my toller is fine but I think it will take me a lot longer to recover! I had a lot of people say to me that they thought it only happened to large breeds which clearly isn't the case, and hopefully my post might make someone think 'I have a smaller dog but the information could still be useful'.