I allways use the in-flight mix. I set it up for full power on takeoff and once I get up and going I richen it up a bit, and then half way into the flight I richen it some more. As you burn fuel the head pressure goes down, so the mixture starts to lean in, so you have to compensate.

I would put them on the same channel, set the needle on the ground and then use in-flight capability to richen them up and keep them that way through the flight.

Steven