To those of you who will receive your M15's shortly - wondering if when you do you could post briefly about balancing on the pan axis with the new dual pan tube structure. You can still do fore/aft movement, but the second part of the pan balancing (the twisting part) obviously you can't do anymore. I have contacted Freefly and asked and they said: "The dual top tube has completely eliminated the need to do the second part of the pan balance process you do with the M10. All you need to do is the first step, fore and aft, and you are ready to go." Guess I'm just curious as to why that is... and how well it works.
Rotating on the lateral pan tube (ie rotating the pan drop tube left and right) if not at right angles, could factor into other balance relationships, such as provide static balance on the pan motor for a given rotational position around the pan motor (I.e. just that angle). By maintaining the right angle relationship between the lateral and drop tubes of pan you are forced to balance the pan fore-aft and the lateral roll balance (the outer latches at the IMU) accurately. This simplifies balancing.
Christropher no need to do the rotation. Same on the M5, it has a keyed pan track and no rotation needed.