I think the back sweat bothers me less than most, but I rarely wear a camelbak unless I'm mountain biking. I do like to bring a camelback if I can afford the weight and space. They are great day packs and hold small articles well. They are an additional 3L of water storage, which may be handy if you are in remote areas where water services are limited. And they are fairly insulated and keep ice water cold on those hot days, if you can get ice.
If you normally ride with one, bring it. You can always mail it home if it doesn't work out.