I am curious about how smooth (or not) the raising and lowering action is of a FEL and backhoe on a 1635 or 1643.
While I don't have any experience with that model, I think the answer is how much experience you have with it. When I started running a hoe, a clear field was a requirement. Now I'm pretty smooth on one.
If it's too fast, back off the throttle a little until you get 'in the groove'. In close quarters it's wise to back off the throttle anyway.