Hi Arne,
I definitely see your points. However, only if a boat got a lot of canvas does not mean that the skipper needs to push it to its limits (like I am doing right now with Ilvy). You can always reef down, especially with a junk. Sailing a slightly overcanvased JR gives you the opportunity to point high and be fast - if you want it. If not, there is no downfall of sailing with some panels reefed, is there? To make my point again: having an overcanvased junk sail does not mean that you are sailing overcanvased. It only means you can set more sail in low winds (or higher, too) if needed and wanted.
There is more to it: if you are undercanvased, you might tack less easily, you might fire up that engine earlier in low winds, you might just have less trust in the sailing abilities of your rig - at least that is what we experience, also in comparison to other junks we meet along the road.
Yes, we are heavily laden! About 10 cm lower now than in daysailing mode. It happens when you have such a roomy, well designed boat as the Maxi 77 and provision for 5 months... Still, just yesterday we overtook a brandnew Beneteau 37 on a beam reach. The owner just smiled at us and took his hat. However, speed is not much more than thin air. What is more important is that we are able to sail through passages where every other sailboat around us hectically takes down its canvas and starts motoring!
We met dozens of Maxi 77's. Unfortunately only in harbour. There is yet one to come which sails with us.