Canvas has faster load times, and depending on the browser, really good caching. There is also caching at the canvas level available. I'm created an isometric rendering engine drawing from a SQL database with fog of war. Even with the map completely visible, repainting on every mouse move is fast in chrome. Would it be nice to have layering without repaint? Yes, but there are other algorithms to speed that up (which I haven't implemented since Chrome is so fast right now).
Here's the other advantage: mousewheel to zoom, click drag to pan, right click to inspect, left click to move/interact.