I hear you all on the weight.
The source website claims that that bag and bladder weigh in right around 12.8oz., bag= 8.8oz and bladder= 4oz.
i am sure that i can find or have made a lighter bag like Like found, but i really an a fan of the source bladders. The one inside the bag that i started the post with seems perfect for this application do to the large thin size (max width of 2.6"). As far as bursting goes i dont know what you all are doing in the hills but that is a non issue for me.
Joe you are to right on how awesome hydration bladders are and how they are not so convenient in packs!!!
I have used some great technical packs over the years and most of the time there is at least one feature that has me scratching my head, wondering why its there or what its for. So I purchased a (hopefully) comfortable frame and a big blank bag to start my (hopefully) perfect for the time pack. I need a bladder when in the hills, I also need it out of the way and close to the body. After all a full 100oz bladder weights 108oz.