FD,
Be very wary of intervening with selected speed - it tends to de stabilise everything and I have seen some low energy arrivals with guys not trusting GS Mini.
The other thing is some of our 'other' colleagues seem intent on using manual thrust on the Airbus........ Boeing throwback I fear.
Then they try and chase a moving target - fail and it is a real buggers muddle.
GS Mini works well, on 320, 321 and 330. The only thing is, you need a working brain to realise what is happening and on the 330 you need to anticipate the thrust couple effect when flying manually.