I always liked feather tracers on my hunting arrows, then they went out of production or, at least, they couldn't be found. Didn't know they were back! I don't remember them causing any differences in arrow flight, but it's been a good 20 years since the last time I had any.

IMO, when you put the tracers in front of the feathers, they're just decoration. You can't see the tracers from behind. If you want to use them as tracers, put them between the feathers and the nock.