Welcome to the adventure of obsession over gear!
I agree that the Double Rainbow would give you the best bang for your buck to save weight.
My friend has one and is very happy with it, plus it is well rated in the BPL review of it.
If your goal is to cut weight and get as low as you can, then I would say save your money and take the leap of faith into the world of tarps, bivies, and quilts.
I did that with the MLD poncho tarp and MLD Soul Side Zip and I have not looked back. (I still have my Contrail Tarptent, but have not used it in well over a year). And I have recently purchased a JRB Sierra Snievler.
All very light and the quilt does give some flexibility to you in warmer weather to vent....that said, I think that it is a fair argument to say that a sleeping bag can be turned into a quilt by unzipping it. (My initally impressions after two nights of use are that a quilt is definitely not as warm as a sleeping bag, but offers freedom of movement. I am a cold sleeper).
Note: in hind sight, I would have been fine with the Superlight, which is half the weight of my tricked out Soul Side Zip.
Buy your backpack last, once you have dialed in your gear, you will know how much space you might want to need.
Advice: if you are going into the Sierras a lot, you probably want to account for the need/requirement for a bear vault, which might restrict your choice of backpack or maybe it means you have two packs.....one for bear vault trips and for non bear country trips.
Sure that I speak for everyone here, but this is more than a matter of buying a list of UL gear. As your experience and knowledge increases, you will feel more comfortable going lighter and lighter, which leads to buying different gear.
Think it is an evolution that all ULers go thru.
Increase skill/knowledge = opportunities to go lighter.
For cooking you might want to consider which direction you might want to go: Canister, esbit, alcohol, or woodburning.
Convience vs. weight.
Midlayer/insultating layers: synthetic or down.
Down is lighter, but if it gets wet, you are screwed.
I chose to go with the "heavier" synthetic as a margin of safety, just in case...despite that most of the conditions that I have been in have been without a drop of rain.
Ask yourself how far are you willing to pushing your UL limits...what is your acceptable margins of safety that you are comfortable with.
Once you know that, it might reduce your buying replacement gear.
Example: My Montbell thermawrap jacket has been the only UL insultating layer that I have bought...love it, no plans on replacing it with something lighter.
Anyway, ranting a bit, hope this helps you out.
Enjoy the adventure in gear!