You should be thankful you or your friend never had a problem. But in the event you did have a problem with the motor, you could be in for some trouble seeing as conditions can change in an instant on the big water.
I agree with the kicker as a back up incase the big motor dies, and for the simple fact that its easier on the wallet to replace a kicker that has been used mainly to troll, rather than wearing out the big motor from trolling and having to replace it. This especially holds true if your buying brand new and don't have intentions of upgrading anytime soon.