A drawback to using extremely light line is that a good fish may pop the leader on the strike. Believe it or not, this is a common occurrence. When you're trolling with a set of pop gear, all of the rotating spinner blades act as a water brake. You're pulling them forward, and the fish is trying to pull them backward. To offset this potential problem, fish with a loose drag setting on the reel.
Speed is important.
Most serious trout anglers swear by rowing vs. using a motor. A gasoline-powered outboard generally won't idle slow enough for that perfect trolling speed. Electric trolling motors have really improved. And with so many models on the market now, there are endless trolling speed possibilities. And they're quiet.