I'm not too clear why such a mechanism is really needed, years of helo simming
Well, you don't need this stick at all. In fact you don't need a joystick at all, keyboard control is all you need :P
I never had a problem using trim functions in sims or felt the need that a hardware solution was required. Although I think by the time DCS Apache rolls around it might be a nice to have.
The traditional solution in helicopters sims (with regular joysticks) so far has been to put the joystick where you want center to be, press the trim button then have to quickly return the stick to its actual centre (which causes the helicopter to move about a bit in the time it takes to move the stick back to centre. See some of all the discussion there has been about Black Shark's trimming system (e.g. http://www.youtube.com/watch?v=AobTSeYyTNo
)). It's this having to return the stick to centre which is the part you wouldn't have to do if the stick had a mechanical force trim built in. Instead the centre would move where you have the stick. And as a result the helicopter wouldn't be making movements every time you trim.
You can simulate force trim with force feedback, and I have tried it in Black Shark. It does make controlling the helicopter much smoother, although it doesn't work perfectly (not sure if that is Black Shark or the stick's fault. But it doesn't always change the centre position to the correct position). But I assume this stick will not be force feedback?
That said, £130-150 to the cost is quite a bit, so I can understand if many feel that is too much for this feature.