Let's try to keep this in perspective.. The a/c does not achieve X FPM after losing an engine on take-off.. the a/c does not achieve anything without inputs from the pilot.
What the aircraft 'can' do, with a company test-pilot on a good day who is knowingly going to demonstrate the EFATO characteristics and achieves X FPM climb is not what the average pilot is likely to achieve when faced with a once in a career real life incident where the first few vital seconds are wasted in confusion.
If this poor guy got it wrong it's quite likely that many others out there will also have got it wrong.
As an ex-FlightSafety instructor with 3 yrs of sim training professional pilots under my belt I can testify that it takes practice on a regular basis to achieve a decent standard of handling an EFATO situation and that's when we know what's coming. In real life this event will in all probability never be experienced by the overwhelming majority of pilots flying modern turbo-props/turbo-jets. Without regular training in a quality sim once might be one time too many.