During the peak of the ocean salmon season last year, a 6" or 7" plug accounted for most of our largest Kings. I always had at least one, some times four out (at different depths to reduce tangling) at the same time, while fishing for chinookasaurus.
Misses a lot of strikes, but with chinook fishing like that, who cares.
One time this past July, I was trying to fish the deep plug off of 300' of DR cable. It was a problem keeping it in the clip. On the retrieve after a pop-off, I had a big King take the plug right behind the boat on a blue bird sunny day. Missed the fish, but the aggression of that fish still suprises me. It took it in plain sight.
I like big plugs but wouldn't suggest using them inside sound.

J.D.