I have a speed reducer as well as a servo and it's great, you can have both hands on the article and don't need one on the flywheel to start off. It has taken me a while to get used to the fact that I don't have to depress the pedal and let the brake off to turn the flywheel, I've nearly been caught a couple of times especially so since it is so quiet you forget it is live and ready to go. The servo just makes things so much easier.
Tony.