It all depends upon what you are referring to as a "disaster". If the fly line breaks under such conditions, i.e., 12-15lb leader, you were definitely in need of a new fly line! As the world's record large mouth is under 25 pounds, and tarpon weighing in excess of 200 pounds have been caught on fly tackle, not to mention even larger marlin, I fail to see any cause for concern.

aged_sage