For trout, I've never felt that I've lost an inordinate amount of fish due to hooks that have the barbs crimped (I do this on all my trout flies). For some of my saltwater fishing (which isn't much), I leave the barbs on...don't really know why because I really hate taking out barbed hooks on really toothy fish...
one nice thing about barbed hooks is when you crimp the barbs down, there's that nice little bump that sort of acts like a mini-barb but it's still really easy for you to get the hook out...
I didn't read all of the responses but that's my 2 cents...
~Randy