I have done wilderness trips in Canada for the past eight years (river trips) and have used exclusively blue barrels for food. Thus far I have never had any issues with bears. We do not hang our barrels, we seek a spot some distance away from the camp site, off the beaten path and attached them with cables on a tree trunk in such way that they cannot be tipped over. Blue barrels are not bear proof but they can minimize food odors and make it difficult for a bear to open (assuming there is a clip in locking band). If the bear can roll the barrel to its side he will jump on it, damage the locking band and the barrel will open. Unfortunately, in popular areas in the BWCA or Quetico, one pays for the sins of previous campers. Obliviously the cubs in the clips knew there was food hanging up there and they had been successful getting to it in the past. If one does long portages it pays to get a good harness especially for 60L barrels.
Full Size Sail Rig
Classic Freestanding Rack