Nope, no leakage problems. I also like that I can use the bottles with a hand-strap and the shape is more comfortable for my hand. I have a Nathan hand bottle that I hate. The flatter Amphipod shape is better for my hands.

No bouncing issues, either. The belt fits snuggly and the bottle/pack really sits nicely in the small of my back. Easy to clean, too. I throw the belt in a delicates bag and wash it with everything else, then hang it to dry.