The best multi-speed transmission

[MrForbes]

In your case, you apparently did not have to sacrifice anything for the weight savings. In our case, bulding our own lightweight transmissions would mean not building the rest of the robot! due to limited resources.

I think if you set the weight budget about 10 lbs under the max weight allowed, and you keep track of it during build, you can probably get the robot done within wieght. Also if you start with a heavy drive base, it's easier to shave weight off it at the end if needed, than if you start with it as light as possible.