I am also fond of my hydration pack.
Before using it, I would stop, drop the backpack, get the bottle out of the pack, drink a mouthful or two, wait a bit, drink some more, put the bottle back inside the pack, put the pack on my back and start walking again..... hen I would have to walk faster to regroup with my hike buddy, who didn't stop to drink ....
Now, I just nibble on the hydration pack's mouth piece from time to time, each time I feel like it, while walking.
it sure no longer breaks the rythm of my walk.
And I'm better hydrated.

In addition to the hydration pack (about 1.5 liter), I also have in the rucksack a 1.5liter plastic bottle of mineral water and and a sturdy 1 liter aluminium canteen. Should I fall, the plastic bottle may break, but the alu canteen should resist. That's my emergency water reserve, the one I do normally not drink during the day hike.

No Nalgene bottle up to now...

I still have to stop sometimes.... to empty my bladder ! <img src="/images/graemlins/blush.gif" alt="" />