I absolutely love my Tomahawk backpack. I used to always forget to change my bladders and they would get nasty and taste bad, but now I just take out my bottle when I'm done and throw it in the dish washer.
Nice but with some negatives
The jetflow Tomahawk is great at first when it's clean and fresh out of the box. But after a couple uses (over about 2 weeks) the liquid coming out of it just didn't taste right. I cleaned it with extremely hot water and flushed out all the tubing and that brought it almost back to normal. The amount of effort and time it takes to get the valves and hoses completely clean AND DRY on this thing mitigates the benefit. If you leave it wet it will mildew.