Eurobolkow, not wishing to go off thread too much, the figures manufacturers choose to supply can inevitably lead to a lack of information and often treating like with like can be difficult on the numbers freely supplied - such was the case with the Grand last year.
The same applies with actually getting bums on seats, you can have all the numbers you like [including that elusive cabin volume] but it is only when you sit down with a crick in your neck that you may be able to highlight that a given type is best avoided by 6 footers..... and that affects an awful lot of airframes.
In this case, as the 429 was 'just a mock-up' it may have been wiser if Bell had followed Agusta's lead and deleted the tail for the launch.