Summit the week of the July 20th.

Is a down jacket needed for summit or camping at 10k' the night before? I have a wind/rain shell that I layer with poly fleece and performance shirt. Worked well for me on similar hikes. The weather forecast looks great for temp and wind with no storms.

As for water, plan to take 3L water bladder with a Gatorade bottle or 2. Water pump and filtering/treatment still recommended for this setup, or just grab some snow and use a few tabs to treat it? Rather not sit and pump for awhile.

If that fleece is thick enough, and the shirt is long sleeve that should be enough. But don't come back and swear at me if you get cold! I myself would take 4 layers--counting a short-sleeve T-shirt.

As for water, I dip and drink - untreated, myself. At Trail Camp, I go to the inlet stream of the pond, not the pond itself. Whether or not you filter or treat is up to you. Be sure to carry 3 liters above Trail Camp.

If you have, or have access to, a light weight down vest is very versatile. I wear a syn top, and carry the vest, poly jacket, and wind jacket. It covers most conditions, I use a shorter/lighter weight wind/rain jacket in the summer and a full on mountaineering rain/wind jacket in winter/marginal conditions. Both of those have hoods and pit zips. The vest comes in very handy for early morning/alpine starts as you can unzip to help regulate core heat along with gloves to keep hands warm. It is also extremely light weight.

Being cold stinks. I'm taking a down jacket at the end of July.

I'm hiking Whitney for the first time in early August, I have a tech tee, a long-sleeve running shirt (Nike Element 1/2 zip), a down jacket (REI 650) and a rain/wind jacket (REI Rainier).

I'm feeling pretty good about this, should I be?

Since neither weigh very much, I always bring a fleece AND a down jacket.