I agree with the food saver. When I go to vac seal any cooked meats, as soon as the meat juices start to flow up toward the open end of the bag, I press the seal button. This keeps even more of the juices in the bag. When done, the bag has no air in it.
I also reheat the meat in the bag thrown into a pot of boiling water. I find that the meat is just a little juicier that when allowing the vac sealer to complete the vac and sealing process on its own.