I will chime in here too:
Maybe turf the rain pants, and use the groundsheet as a wrap-around rain-skirt. It might take some modifications of the ground sheet, but probably not much.
Trade tent for a tarp. But, that was not a comfortable "mental experiment" for me when I was first contemplating it. Then, I did a couple nights in the backyard with the kids, and it started to seem a lot more comfortable. What's more, when it came time to tear down or set up (once I was getting familiar with some simple set-up configurations) the tarp, it was so much simpler than what happens with a tent...that I was sold on the concept. So, try a tarp a couple times in the backyard and you will find yourself converting to a tarper instead of a tenter....but then you will need to have the bugnet head gear.
Then, turfing the stuff sacks for a single bag-liner bag might also free up time and peace-of-mind by just cramming all dry items into said bag, folding the top and throwing in other items on top. That will eliminate stuff sacks.
Next, it might just be me, but do you ever use that dinner knife? I stopped carrying one when I realized that I simply never used it.
Then, the whistle: maybe you could just learn to do that two-finger whistle. I find its as loud as a rescue whistle anyway, and I don't have to search for it to utilize it.
As for the steri-pen...well that is going to be pure preference. I just can't rap my head around that technology. So I graduated to aquamira for weight savings and then took on a two litre platy waterbag. Then, I had a water bag that could be conformed into a pillow (which keeps the water warm at night...or you could warm the water first and use it as another method of staying warm at night), or flopped onto my headlamp to turn it into a area-lighting lantern. Give it a try sometime, its a really neat trick.
I am wondering if that warm hat/bandana can be combined somehow for some weight savings, and maybe even bank-rolled into the function that the sponge does too...but then maybe their will be the issue of the bandana still being wet when you want it warm.