Went for a run on Sunday. The same 2.25 mile loop as the other day, but a little further before I ran out of will power. Running with the CamelBak is still A++. Filling it only half-way seems optimal for me -- less weight and it doesn't quite cause my shirt to ride up in the back. The buckle strap in the front is nice for keeping the pressure off my shoulders but it restricts how deeply I can breathe in, which is a little bothersome at times. But it's a win on the balance, big time.