I like my hydration pack because it is so small, and it has become my go-to-work backpack with no water in the bladder. I can sweat a whole lot, so I prefer water bottles in most cases except mountain biking, where the bottles can get bounced out. I have a long ride coming in August, and am planning to put one of those double-bottle triathlete seat-post things on my bike, giving me a total of four bottles. Until I drop another 30+ pounds, additional weight isn't much of an issue.