Camelbaks - are they worth it?

[love2bike]

Hi - I'm new to the site and just decided to jump in - and just started riding this Spring. Bought a hybrid and ride about 50-60 miles a week on the Katy Trail. Love it! Now, I've commited to ride on my husband's company team for the Gateway MS150 in Columbia MO. in Sept.
We're making the jump to road bikes, my Trek Pilot 2.1 WSD will be ready tomorrow. I haven't been this excited since my last kid was born! I've started my training program, and will start riding longer rides as soon as the !@#$%^%$# rain will stop!
I usually carry about 70 oz. of water in a touring bag on my hybrid. I'm thinking about using a Camelbak for my road bike. I'm a little concerned about the additional weight on my back...

Are they uncomfortable?
Are they worth the money?
I'm looking at the "Magic", "Daystar" and "Moxie" models- does anyone use those here?
I would really appreciate your insight and advice!