What do you need the perfect range of motion for? A sports jacket would probably be more sensible.
In this respect, I would say that if you like the look of gussets, take them. If not, don't.
Does Aero offer underarm gussets at all?
Many of the military jackets they reproduce include underarm gussets. Whether they'd add them to a civilian jacket order, I don't know, but it could be an option.