Uni-knot alternative to slip bobber knots

I had a thought - why not use a heavy mono or fluorocarbon line uni-knot tied to the main line as a slip knot.

http://i76.photobucket.com/albums/j3...pscf357289.jpg

The knot slides up and down and a bead can be used for slip floats to control leader depth. In the picture 20# test line was used over 10# test and the knot on the right was slid closer to the sinker.

I dont have enough confidence in that knot to use it like that. I would like to hear how it works out for you.

The uni-knot is the knot I use for this slip application because it grips the main line great. I also use the uni-knot for most of my other knots.