Is everyone in agreement that Metal boat are a little more volitile than glass when it comes to up-keep?
Not really. I think that when you generalize the material of a boat to this level there isn't much I would agree on at all. Metal is not the same as fiberglass is something I do agree on. To the extent they are different I don't see is an advantage to either. I can identify numerous fiberglass boats that really are quite poor, but I'm sure that the fact that they are fiberglass isn't why they are poor. Poor boats usually have many things wrong with them but the actual base material can be all the same.
A fiberglass boat really isn't all 100% fiberglass. The process and methods of construction become part of the materials and part of what makes some better or worse for specific purposes. Even then it's just the hull
not the whole boat. The same is true with metal. No one uses pure aluminum or pure iron. They all use alloys. The debate on alloys will head
into advanced metallurgical discussions.
The link you posted is a sales advertisement for building boats in New Zealand
vs the US. It seems the company feels they have a financial advantage based on monetary conditions that are unique. That is the only thing they discuss. They then go on to say that one off boats are just as good and a lot of other generalized BS. The article says nothing else about the process let alone the boats.
It's also 2 1/2 years old so monetary differences are not the same as May 2004. It may also say something else. If the article hasn't been updated in 2 1/2 years it may mean they were wrong. I sure don't know based on what I read.
If I disagree on anything else it may be that just because a boat is built in one location or another isn't an argument we really are going to resolve. French boats better than US boats, AU boats better than NZ boats, or similar discussions don't really go any place important. The idea that one country of location is somehow uniquely better gets no place. Over simplified comparisons are not very significant.