I think your list looks great so there really isn’t much to say. I tend to think that you probably will be fine in your bag (assuming it is good to 30*) without the down pants, but you never know. I also question the need for the balaclava when you already have a warm hat and use a bag with a hood. That being said, it is only 1.4oz so it isn’t a big item.
The steripen and associated bottles are a little heavy compared to chemical options, but you can make the argument that it can let you carry less water so in reality that might end up a wash.