[kaliken]

I can speak for my team that coupling a shaft could really help.

The couplers in your link we actually use to link our potentiometers to our shafts. We have both the rigid and semi flexible and they worked well.

I would be a bit worried about torque transmission if I was going to couple the output of a driving shaft so sizing the coupler would be essential.

In that respect, at championships we got hit with the infamous Banebot775 short in our lift gearbox. It wasn't pretty since this gearbox was tied to our lifter drum. Luckily we had a coupling device to connect the drum and gearbox instead of making it one big assembly. If it was a single assembly, it would have been major surgery to take the entire assembly out.

What we had was a home-made shaft coupler. The output shaft of the gearbox and the input side of the drum were both 0.5" hex. So we simply broached a hex into cylindrical stock and added a couple set screws. This allowed us to take the gearbox out, swap the motor and get back underway in minimal time. On top of that, we did a quick look at the torque and loads into the coupler and found it would be sufficient for what we needed to do.