While I had nothing to do with this (awesome) design I think I can take a few of these.
To me it actually doesn't look like there is room to flip it without increasing the bellypan footprint, which may have been a greater design concern than COG or expandability for them.
There is simply no need for such a powerful motor in this application, 1640 has been using the even less powerfull RS-540s in this application for years with no problem. Personally I would use the AM-0912 (which has power between a 540 and 550) because you can use 4 of them and that frees you up to use any of the BB motors on the rest of your robot for things that may require the power of an RS-775
Not sure on this one, it certainly looks like there is enough room for an idler encoder gear down there
https://imgur.com/IwbQ4JL maybe mounting issues, gonna have to wait for the OP on this one.
I would have actually said most notably literally everything else lol, the miter gears can be purchased from VexPro but there are certainly some other complicated parts on here.
I know most teams make at least 1 spare module (if not 4) that way they simply swap the entire module out if anything happens to a competition module. The problem module can then be repaired at home under controlled conditions
Now I have a few questions:
Why the hollow drive axle?
According to the CAD the shifter gears are steel but reference aluminium VexPro gears, what's up with that?
Amazing looking drive, great work, I hope I get to check it out in person at champs!