In my sub-surface lake fishing research from a float tube, I have found that more strikes are had with a non hi-vis level fluorocarbon line than with hi-vis lines such as Sunline orange (the best line I have found for more traditional Tenkara fishing) or the Yamatoyo chartreuse. I believe the short 24-36" tippet/leader and 12 ft. plus hi-vis line combo when presented below the surface still retains a reflective quality that might spook fish - since a good length of the hi-vis line is completely in the water, not airialized above it. For still water fixed line fishing visibility may be a hindrance or at least not the most necessary line characteristic. Without that visibility, however, a relatively tight line and good control become critical to prevent missed takes.