Yeah I got the Navionics app for a while now. I can see the usefulness of it, particularly following channels as you mention. It's also a great compliment to the new Garmin and checking contours, creek channels, points, etc. in most all the lakes around.
And to clarify, no, I wouldn't go looking for specific stumps and rocks with the main motor down. If there's something specific like the Santee rock piles I'd ease up with the trolling motor.