i love my camelback palos 4lr, its absolutely brilliant with no water in, rarely moves, very light and comfy, don’t notice its on at all, I have a bottle on frame so don’t use the hydration at all for night rides/shorter weekend rides
but when its full to the brim of water, it does tend to swish around a little bit and sticks out a fair bit more (giving it more leverage to move up and down), and feels a little more weighty on descents, obviously once you start to drink away it soon disappears
but for me it holds everything id take in a full back pack on a big weekend ride (just less the water obvs) but just not got the weight on my back so its win win, and its so nice on warm nights/shorter day rides not having a full pack on and letting your back breathe