recumpence said:The problem I see with planetaries is the noise. They also add length to the motor.
Matt
The noise of those RC or robot planetaries is sure annoying. I agree with you on that
Thanks for the project links in a previous post. I made my way to this planetary, which I could stick on an Astro motor:

http://banebots.com/pc/P80K-nnnn-0005/P80K-4-0005
But now on second thought I might want something quieter. Guess my options would be:
Bigger low rpm motor.
Belt drive first stage.
Quieter gear box. Not sure what would do the trick: angle cut gears? Oil filled? Would plastic gears be an option?