Lots of good suggestions here – most glaring to me, as mentioned, are the stuff sacks. Zip locks or grocery bags.
Your biggest weight savings are your pack, "tent", and bag. Light can be costly and any discussion about your gear is in a vacuum unless we know where you go, altitude, climate, time of the year, etc.
But, saving all of that:
Pack:
I have that pack – it is great. It's my winter pack now. GoLite Ion during 2-3 seasons for me too. Lots of light packs out there but consider if you can handle a pack with/without a hip belt and with/without a frame
Bag:
I've gone to a Western Mountaineering bag. Set me back but had I just bit the bullet up front and not kept buying bags to shave a couple more oz's here and there I'd have 1 or 2 bags and not 5. Spend the $. A good bag is protection. Simple.
"Tent"
I can now handle the floorless thing but it took me a while to get there. Critters do not bother me but I just liked having a bathtub floor. As with anything you bring try to make it do the work of two. I use a Six Moon Gatewood Cape (my tent and my rain gear) and if going to a place where there is thick compost, flying insects, etc., I'll bring the Six Moon Net Tent to go with it.
There are versions of this which may be lighter – I just liked this one:
http://www.sixmoondesigns.com/shop/shopexd.asp?id=45
http://www.sixmoondesigns.com/shop/shopexd.asp?id=55&bc=no
HOpe this helps. Good luck….

