The difference in low mode between the two configurations is much more noticeable than the initial difference in high mode, IMO. Depending on the ambient lighting available when you're looking in the panels, the ~15 lumens vs ~40 lumens on low may make the difference for you. With low ambient light, 15 lumens is very useful and 40 lumens can be a bit too bright. With high ambient light, 15 lumens isn't as useful and 40 is a great task-light level.
With some experimentation I've no doubt you'll quickly find your preferred setup for the tarmac/flight deck combination. In your situation, you might carry two bodies for a while; an MD2 with 18650, and an MD3 with 18500s. This would allow you to quickly switch from one configuration to another to experiment.