I am now much better able to manage take-off and landing after spending a serious amount of time tweaking sensitivities on the rudder and (critically) toe-brakes. It's now at the point where things are not too mortifying...
I have the following observations remaining (I stress this is ME so probably my flying):
On take-off the rudder is only beginning to become really effective just before 90kts so any attempt to switch to that when the toe brakes have been used to stay straight actually introduces instability so I find it best to ignore
When in a simple straight line taxi at very low speeds, I find the aircraft will veer from the centreline without compensating constantly with rudder (steering). The deviation is pronounced and I wonder how sensitive the real aircraft is to wind? My tests were done with an 8kt 90 deg crosswind which doesn't seem extreme.
When I switch wind off I can taxi and take-off with zero directional inputs. I would expect deviation on take-off as speed is so much higher, but it's purely the scale seems quite large.
Still spending inordinate amounts of time in this and generating a lot of smiling :-)