Last year I got one to three storms per day all except a few days the entire summer! Rain gear is absolutly necessary.

The down jacket is a luxury item - nice to have but like others say, you can always dive into your sleeping bag. You will not hike in a down jacket - too hot. If you do not take the down jacket, replace it with a lighter/more compact layer. I really like wool - Smartwool zip top. Wool breathes very well and is great to wear under rain jacket if you plan on walking in the rain.

The head net is good for back flies as well as mosquitoes and only weighs a few ounces - I would definitely take it. If you do not use it, so what.

I would add one or two bandanas - these also work well in first aid situations. Also think about one very light sponge - when you go in and out of a tent in the rain, water gets inside and a sponge is great to wipe up puddles. If you have never spent any time in a tent during an all day rain, I would make a point to go do it to test out your gear.