We have both a water chiller and insta-hot coming out through one faucet. It's two separate units and they couldn't both fit under the sink so the chiller is in the powder room sink cabinet (the wall is shared between the kitchen sink and powder room sink so this worked out really well). There are different faucet styles available with hot and cold levers as well.

It sounds like you are headed in the right direction, the saddle valve is not a great idea they are not a very good valve and not code. I would get a good compression tee or sweat a tee and a good ball valve for the ice maker. The AAV could go under the sink off from the drain and get it as high as you can. Have fun

In our remodel, we will have external ice and water and a hot water dispenser in the prep sink. Right now we use the Brita and a hot water pot (plugged in 24/7) which keeps water boiling hot but sits on the counter and takes up lots of space. My kids and DH love cold water and miss the dispenser (which is currently broken on my kitchenaid) That was one of their musts for the new kitchen. I LOVE hot water and can't live without it for tea and hot water, hot chocolate. I would rather pull a lever rather than microwave or boil water. SO, for our remodel, my rationale was since i'm getting cold filtered water in the fridge- I would save and get the hot water dispenser in the sink. If the water dispenser in the fridge is that slow..i'll put the Brita in my new and bigger fridge. For me it wasn't a hard decision- it seems overkill to have 2 filtered cold water dispensers. Now I have to look into the energy consumption you are talking about because I am trying to be energy conscience and efficient with this new remodel.

My sister has one. I have to say it is very convenient for making cups of tea. That said, hers is either not insulated enough, or too close to the cold water pipes, as her cold water now comes out very warm too. She needs to let it run for 30 seconds or so, before it turns cold again. Not cool at all!