Noah Howellwrote a review of Mountain Hardwear Fluid Race Backpack - 240cu in on September 3, 2013
Familiarity: I've put it through the wringer
These vest style packs are really nice! Even if you're not a serious trail runner. They hug your body really nice and don't shift around. Tons of handy pockets for your water, gu and phone right there. The only drawback is that they are pretty hot! Because of so much body contact they seem to create more heat and sweat, but that's not a huge deal.
You can actually pack a lot into this model. Plenty of room for a light jacket, camelback, extra snacks, headlamp, etc.