Personally, I always hike in long pants regardless of weather. However, you could switch to a pair of convertible pants and leave the shorts out of your pack if you want that versatility.

If you have the money to spend, switching to a down insulating layer will save you more weight. MontBell's Down UL Inner Parka, for example, would cut that weight vs. the REI synthetic jacket by almost half.

As far as gear goes...an alternative to the photon light is the Petzl e-Lite. It's what I use, however my normal trail day involves setting up camp, cooking dinner, cleaning up, and hitting the sack by nightfall. I almost never use it, it's there as "what-if" gear.

Lots of weight savings to be had by switching to an alcohol stove, however that may not be conducive to your cooking style.

Now being REALLY anal ...in your first aid kit, ibuprofen would probably do the job of the excedrin if you're treating a simple headache vs. a migraine. For that matter, if you switch to a longer-acting NSAID like naproxen (Aleve) you can carry fewer pills. Most of the time I'm popping pills it's for joint-related pain from overuse syndromes anyway, which is what naproxen was designed specifically for.

Jealous of your trip itinerary, no mountains in my neck of the woods