MDA, unfortunately your argument doesn't have alot going for it. You cannot compare pass rates on checks-to-line directly with the type of interview process. But I do think you can compare individual training regimes and interview styles.
Airlines will develop interview techniques and standards with their training procedures and line operations in mind. So one example might be; any deficiencies in training resourses available has to be a major factor in deciding what skills and attributes the interviewee must have from day one. Possibly an example of looking for the 'just add water' co-pilot in Eagle Air's case due to the specifics of their operation and therefore their need for a more in-depth interview process.
Air Nelson would be a good choice of a first airline job due to their good training resourses and procedures. But with this in mind I suggest that the need to be more selective during the interview process is of less importance due to the comfort of training resourse available.
I think you were right though, when you said
Air Nelson do a 45 minute personality and knowledge interview and that works for them just fine
in particular
Joseph is right, after reading toby jac's post you have to wonder why the process is not condenced into one day. Instead of having 9 guys for 3 days, possibly 3 guys each day for 3 days, reducing costs to the individual.
The main point is to realise that to compare different companies' procedure's is pointless unless said companies' are similar in type,size and operation. Failing that it will be too easy to debate without resolution.