I've been using the fish flash with a deep6 for 3 years . Advantages, choice of colors and sizes,spins on it's axis so less drag.
Disadvantages,given a chance it will twist everything near into a tangled mess.
I'll not be going to downriggers anytime soon so I purchased a Cabela's depth guage to attach to a diver, and a line counter reel. I now know exactly amount of line out and depth diver takes my gear.
When using a hoochie or squid without a cut plug herring you can get action by doing away with the swivel and attaching to the flasher with just a clip. Use heavy line and check often,this gives a great roll but will not work with light line.
IMHO this flasher out fishes all others.