Fluorocarbon is quite stiff which is great for hoochies which will get a real snap off the flasher. The line also sinks like a stone as well as being almost invisible.
As you are using it for mooching, you don't need to worry about lack of stretch as there won't be something like a flasher to add inertia when a fish takes off. I used to mooch with no more than 12-pound test leader, usually 10-pound...unless you're really ham-fisted, it's gonna be really hard to break 25-pound test.
At the boat, be patient and loosen up your drag a bit. I wind the weight to the tip of my rod, but when I arch back to bring the fish close, I keep my fingers away from the reel handles, and only pinch the line against the cork for pressure.
That said, do you really want to pay the price premium for fluorocarbon line...salmon don't seem to be that fussy about any kind of leader if you're motor-mooching. Anchor mooching....another story...
