Hydration Pack or Bottles?

I'm contemplating my hydration plan for the upcoming 100-miler this weekend and am faced with the choice of using a hydration pack or bottles or a combination of both.  I have a bike with only 1 bottle cage available so regardless of which option I choose, I'll have a little water on my back.  For The Bailey Hundo this year I opted for a pack swapping out a pre-filled bladder 1/2 way through the race.  For last weekend's race I used bottles and had a teammate 1/2 way through each lap hand off a fresh bottle in addition to a stash at the start.  So based on my experience here are some reasons for or against using a Hydration pack.

Hydration Pack Pros:
* Easy to grab that little hose and suck even when in technical terrain. This makes staying hydrated easier.
* You can cary a little more water and save time passing up aid stations.
* A little more room for an extra vest, tube, food, etc.  You don't have to stuff that jersey to the limit.

Hydration Pack Cons:
* Weight, you have to cary more weight on your back rather than on the bike with bottles.
* High center of gravity, almost a guarantee the pack will slosh around and throw you off balance at some point.
* Hard to know how much water you have left.
* Takes a long time to refill.  Bottles are much faster to swap out and / or refill.

I know each pro / con doesn't cary equal weight and the terrain of the course, frequency of aide stations, etc can swing the pendulum one way or the other.  Still with that said, I'd love to hear your input on the topic.