hand held bottles

My system...

If I can do the run with one bottle, which for me is in the 6-8 mile range, I go for the hand-held. Didn't used to like them, but I got some freebies at a couple races and kinda started to like the 'freedom' from the hip and back mounted water. You get used to it and I like to think I'm getting a little arm workout too.

Runs that require 2 bottles, often 7-13 miles, I take a running fanny pack with 2 bottles in it. I like having my back unloaded if possible. A fanny pack is a good balance between more cargo capability, and still having a free and open back.

Runs longer than 13 miles that take more water, I have a Nathan backpack I run with. Not really my best preference, but for longer runs, its really the only thing that does the job for me. I have a couple Camelbacks for Mtn biking, but they don't sit right for running, and too heavy. The Nathan works/fits well for me.

Honestly though... I really like having a number of options to go to and not just be locked into one hydration setup.

I like my hand held so when I trip and fall, it breaks the impact somewhat

I have lazy feet and tend to look around way too much.

For me, the choice between pack vs. handhelds comes down to two factors: the heat, and the distance between aid stations.  If it's hot and the aids are 3-4 miles apart or less, then carrying handhelds allows me to run shirtless, where my core can stay much cooler and I feel like I can run faster because I'm more comfortable, so that's my preference.  If it's cool out, then I go handhelds because I don't need as much fluid.  

But if it's hot with 5-6 miles between aids, like at my last 50 miler, then I go with a hydration pack until the last 10 miles, where I ditch the pack at my drop bag, ditch the shirt, and run as fast and hard as I can with a handheld.  Unfortunately, I can't see a way around having to wear a shirt under the hydration pack, or you're looking at a painful rash.  

I seem to be better at remembering to drink when its in my hands. 

I can go either way, but typically use handheld unless the aid stations are sparse or the temps will be high during the day.  It does suck when you start to trip/slide down a muddy trail and try to grap onto a sapling with a bottle in your hand...

then again it can be used to help break a fall, win some/lose some.

I've also heard it is easier to monitor your fluid intake with hand bottles than with a pack.  If you are running with a full pack and refill at aid stations, how do you know how much they put in?  Sure you can ask but it seems very subjective.  Also, the hand bottles allow me to carry some kind of sports drink since I don't like to mix that in my pack.