All great questions. I'll begin with the caveat that any of my assumptions below may be totally wrong, so feel free to correct me
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First, apologies for the naming convention-- the "mm" in both names were just to indicate to the manufacturer that both files have units of mm, as STL files apparently don't have the units embedded. The two files are version 6 and version 7. The newer one (7) has smooth tubes for the passages instead of sharp internal angles. I use the Multijet Fusion process, which involves laser sintering a bed of nylon powder, and the excess powder has to be cleared from the interior afterward. With version 6 it was difficult to clear all of the powder from the interior, and it was more difficult to clean generally. With version 7 it's pretty easy to clear the powder with compressed air, and the vapor smoothing process is more effective. Also, 7 does have a smaller internal volume, which could speed response time a tiny amount. I'm doubtful that it would be noticeable
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One of my primary goals was to make the route for moisture to get to the sensor as difficult as possible, hence the relatively "tortuous" path to the sensor. It seemed that having the connection to the sensor where you've shown it in green would be a more direct route, especially if the player is holding the instrument down at an angle, as I've shown. With the instrument in a normal playing position, the moisture actually has to travel upward to enter the sensor connection.
Also (this part is definitely conjecture on my part), I felt that because the airflow is directed toward the area you marked in green, more condensation would occur there, so there would be more liquid on the outside of the bend, and that liquid would be forced by the airflow around the outside of the bend and out the "nozzle".
Finally, I wanted to make the mouthpiece as quiet as possible, and I was afraid that a hole on the outside of the bend would result in an acute angle and act like a fipple, causing a whistle. The air velocity is also higher on the outside of the bend, so I wanted to interrupt the airflow as little as possible there (again to reduce noise). Having the hole on the inside of the bend results in a relatively quiet obtuse angle.
Hopefully that makes sense!
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