I'm assuming the small heavy one gives more control and the bigger lighter one gives less.

What would the advantage be of one over the other? I'll be using the medium size on a 4*60. Which is the recommended one?

They're easy enough to change. Try one and see if you have adequate control. Sometimes the softer spring makes it tough to turn, especially on a grass runway. Give it a shot and if you don't like it, change it.

Rein