Dear Sidestickbob,
I'd say there's nothing wrong with "F-speed" in the case you describe, but A/T is to blame for not keeping it!
Are you flying in a company where A/T is mandatory at all times (and an A/T failure would be a major emergency?) If so, that's a shame.
If however you are allowed to use manual thrust in the Airbus, please make sure that you get enough practise to use it with confidence!
Believe me: after a little practise, any pilot will manage the thrust better manually then the A/T system.
Please read
this earlier post I made about A/T use in the Airbus.
Regards,
Sabenaboy