The lighter the line you use the further you can cast. This only matters in CLEAR water lakes like Dale Hollow and Cumberland... Fish in 10 to 12 feet of water can see you if you are too close so you need to cast from further away to fish for them.
Power pro in 8 pound diameter 30 pound test casts good, but power pro in 1 pound diameter with 6 pound test casts MUCH further. I tried it with Bob last week and the difference is IMMENSE in casting distance.
It is the friction of the line comeing off the reel and going through the guides that lets you cast sooooo much further.
Jim