Thrift is key to being an effective fisherman, anything removed from your set-up or pockets is a win, and anything not on your line is a win. I would not use two swivels simply for the fear a fish will choose to grab that instead of my presentation, I also don't use slinkys for the same reason, a 3 inch long black object is practicly a spinner.. might as well put a hook on the thing. I have seen and felt so many fish hit swivels and slinkys and hollowcore. Swivels are fine, and a great device that weights next to nothing so its not much of a weight or space commitment... but, anything you can streamline and clean up should be. I personally use a barrel swivel on my bead set-ups to facilitate re-rigging faster when its cold out.