Areas of smooth, solid color (like skies) can show the inconsistencies of the sublimation transfer process. Images that have lots of fine detail (like your wavy water backgrounds) can mask these imperfections and work better. Larger prints like 24x30 and greater show the wavy, not perfectly flat nature of these metal prints, so I generally encourage people to use then for smaller sizes. Some print vendor mount their sublimation metal prints to more rigid backing which makes them perfectly flat at larger sizes but adds to the cost.
Mostly importantly, how will these be presented (floating, tin a frame, etc) and how will your client base receive them?