i dont know how they affect fish mouths, but they are night/day difference in ease of untangling from my fishing line.  you can almost shake the line out of the hook.  inside barbs, not so much.

 

i kinda love them.  

Just don't get stuck by them,... Braid trick doesn't snatch those out as easily!!!

I use outbarb Gami 510 for deepsea SPJ, I make my own assist hooks, It is way cheaper and I can do single hook one up and one down(CA rule). This outbarb hooks are so much easier to remove from fish mouth.

 

I have a handful I use for northern pike