So far I have only five years' experience with a Sileno Smart city 500, and I am very satisfied. From what I understand, the main difference between the models is the autonomy and therefore the capacity of the battery. The cutting system is the same, and if the result is not as expected (uncut patches) just increase the working time. It is important to cut regularly, ideally 6 days a week with a day off for the lawn. However, the GARDENA instructions are clear and easy to follow.

I can't say that. I have the Smart Sileno City 600 and it mows very well. I'm very happy with it. Our area tends to be smaller than 250m2. The speed doesn't matter to me.