I've used them off and on for the last three years and here's what I have found.
Slow trolling only on the rudder style. Doesn't seem to make any matter on anything larger than 10 pound fish.
Was given just the e-chips and installed them on hootchies and bait, again didn't have any effect on larger fish.
Where they did work, is on Sockeye, in Alberni. Both on the hootchie, baitbuster lure and the flasher itself. Conservatively increased catch by 25%.
Springs and Chum, made little or no difference.
I think colour choice is more important.