My experience with hammocks ....
At home I sleep on my side and move around a lot; in my hammock I have been known to sleep 12 hours and wake up in the same position I fell asleep in. I also wake up with none of the lower back pain that I have on a regular basis.
As for weight, my hammock set up is slightly heavier than my ground set up. On my last 3 day, 2 night trip, upon returning to the car, my pack weighed in at just over 13 lbs, with still a day of food and many luxury items ( down pants, down booties,extra socks, big fuel canister....).
That said, hammocks are still not for everybody. Maybe you could ask someone to loan you one and give it a try.