@pauld firstly, do not use default aircraft as reference. The figures used in them bear no relevance to actual, calculated aerodynamic coefficients. The default 747, for example, has a pitch damping level a few hundred times higher than the calculated figure and therefore it also has a pitch moment and MOI similarly distorted from reality in order to balance it. The VC10 MOIs were calculated using a real-world aerodynamic tool.
The elevator has had to be created very differently, as it is an all-moving tailplane. The simulator does not have any way to deal with this, it expects a horizontal tail and a separate elevator. By overcoming this obstacle in the sim's core flight model, it introduced further issues which had to be dealt with, such as the lower deflection angles of the 'elevator', which is where I suspect the trim effectiveness was adjusted to compensate (though it is several years and multiple aircraft and sims since I worked on this).
We had a recently-current VC10 pilot on the test team, and he was quite specific about many aspects of the pitch (especially the slat / flap behaviour) so I would be very surprised if he passed over anything as bad as you make it out to be. I do wonder if it is an FSX v P3D thing, as the latter was where this was primarily tested. Unfortunately, I no longer have FSX on my system.
