ChrisK - congrats on having found a good approach to avoiding the need to babysit them. For me, that is one of the great benefits of these techniques that provide a bigger reservoir of water, together with some siphon effect. Glad for your success!
I use a similar technique for keeping the Christmas tree watered too, when I go away. (I keep it in a regular stand, but when I go away I put a wide (but relatively shallow) bin next to the tree stand, fill it to the height of the water already in the tree stand, and then connect the two containers with a water-filled tube. Even though the tube has to rise above the rim of both containers, because it's filled with with water it effectively acts as one big reservoir... as the tree drinks water, water siphons from larger "reserve tank" through the tube and keeps the water level in the combined reservoirs even). It's just a way to increase the size of the water supply without having the risk of valves and such.
Mike