I use tigon all the time down to the UATs. But, I also inspect all fuel tanks every two years. Frequently, during my inspections, I usually replace the internal clunk lines. I usually end up reusing the external lines. However, on my Sprint, I have not replaced the clunk line in at least 4 years and it still moves around O.K.
I have used clunk line with and without hardline installed. Never noticed any difference. I use mostly 3/16ths tigon. I think one would be hard pressed to find an install where 3/16ths tigon doubled back over on itself.
I don't use felt clunks. I frequently can not get them inside the tank anyway due to the clunk being to big to fit the tank's fitting. I stick to BVM's heavy hi-flow clunks. Got them in all my gas planes too.