Yea this looks like a fun build project. It is fun to come up with new ideas and try things that others may have failed at, but in the end you learn more about R/C design and construction.

It kind of lets you see exactly what some of the manufacturers have to go through in order to come up with a half descent vehicle.

Trial & error is the best way to learn.

I do like that piece of channel you came up with, and for free. Can't beat that with a stick.
Considering the sheer size of your build, the size of the 1717 motor and the added stress you are giong to put through this thing you really do have to elliminate your drive line weak points.

Using plastic in any of your drive line IMO is just asking for trouble.

If you want this thing to last for any length of time get your diffs all setup in alloy to avoid inevitable failures.

If there is any way to use hardened steel gears I would do it. Alloy diff cups and cases will give you ultimate strength, reduce flexing, and help avoid disaster and more delays.

Just my 2 cents. Nice project, keep up the great work, and thanks for sharing your experience with us.