when it is quite safe and comfortable to hand fly, without overloading the PNF
I can't believe what I am reading here! "Without over-loading the PNF?"
Why on earth should the non-flying pilot be "over-loaded" if he is a competent pilot. Go back in aviation history to when real men were flying wartime bombers with the most rudimentary autopilots and getting shot at and no weather radar either. Hand flying was the norm and the copilot did his own job waiting to take control if the captain got hit. And no one complained then of "over-loading" the copilot.
Get a grip. Of course common sense dictates that full use of the automatics in modern airliners maybe operationally necessary to keep within tight tolerances on some noise sensitive departures. On the other hand, following the flight director if manual flying the departures will also keep the track within tolerances. After all, isn't that why aircraft have expensive goodies like flight directors?
Much of the objection to keeping one's hand in by hand flying, comes from those who are well aware of their own lack of piloting skill, and assume others have a similar inadequacy due either laziness or personal apprehension of exposing their rustiness to a keen pilot in the other seat. But "overloading" a PNF? If that is so then the PNF needs re-training to enable him to cope with his normal duties.
A pilot should be equally skillful at hand flying without the benefit of flight directors and autothrottles, - and at full use of automatics. 50/50 - not 70/20, in favour of automatics skills. Until this is accepted, then history will inevitably repeat itself and accidents will continue to happen caused by loss of control - in fact Loss of Control has already overtaken CFIT as the leading factor in airline aircraft accidents.