Just as an option for trolling with the optimax you may want to look at a 5 blade High Five prop and the SmartCraft Tach and Speedo gauges so you can control RPM with the troll control features. If you do lots of trolling, you may have to change or clean plugs a little more than normal if you notice a decrease in the performance of the opti during the fishing season.
I guess with the recent invention of 4 strokes people started trolling, not sure what we did when all we had was 2 stroke motors.
I think you will be fine with either motor, just prop it right for trolling.
Enjoy your new rig.
-s