I apologize for the absence of a dedicated topic, but when the subject has been (partially) discussed in the other thread the idea has been kind of accepted and the new template seemed necessary (to some extent, at least).
As for the utility of the article itself - as I stated elsewhere, the result of research based on canon might not be shared by the community as a whole. Who came out with the "Apocryphal" and "Pseudocanon" terms when analyzing the potential validity of jump nodes that don't appear on the official node map, which is even supposed to override any other canon source? I don't agree with that analysis, and I obviously can't edit that article according to my own opinion.
Inconsistencies article are only an example. There are major assumptions in "Retconning in FreeSpace" and "Post-Great War era contacts with Sol" whose validity may be questioned by many community members.
The Non-canon template, IMO, should be used for articles of ambiguous validity: non canon planets, stars, historical events, ships, weapons and such should all go to that category. In other words, it's to be used when the content of the article may be interpreted as canon if the much needed explanations aren't provided. Without the non-canon template, for example, it would be impossible for the average Wiki user to know that the Tegmen system isn't canon. Additionally, I think that pure non canon info should not be debatable: if I say that the SSJ Gigas first appeared in the INFR1 mission "Gigas", no one can complain about my statement and no one can claim that Gigas and the SSJ Gigas are canon. IMO, the non-canon templates is for facts, not opinions, based on custom-made campaigns, models, weapons, etc. etc.
The template is redundant when the nature of the article is obvious: we all know that Shivan Theories (most of which have a community member's nick on their name) are not canon, so what's the point in adding the non-canon template? The same principle can be easily applied to the Shivan Manifesto: considering it "non canon", IMO, is not enough giving the number of critiques (which were enough in quantity and quality to have their own article). It means that many members of the community don't agree with the Manifesto's writer and obviously can't edit the writer's original article according to their critiques. That's why we have a "Criticism of the Shivan Manifesto" article. "Non canon" means that Volition is not behind the creation of the article, but it doesn't mention at all what other fans may think of the article itself.
Specifying that an article has been created by one or more fans and therefore does not represent the point of view of Volition nor the point of view of the FreeSpace community as a whole opens a new scenario. It allows contributors to make major (and hopefully reasonable) assumptions on the FS universe without having to deal with people who don't share the writer's opinion and point it out as trash (it happens on the forums so imagine what might happen on the Wiki). When it comes to this kind of theories, pointing them out as "non canon" is not enough: "non canon" defines info which haven't been confirmed by Volition, but somewhat implies plausibility and proximity to canon.
There are many articles on the Wiki that should, IMO, have the new template instead of the more specific "non-canon". The idea behind the new template, is not new at all (as seen in the "Shivan Manifesto" and "Criticisms of the Shivan Manifesto" articles, which clearly show how "non-canon" is not enough). It's just that, IMO, it needs to be applied even more...
I agree with TopAce: the template may need a name change. I created it following the result of the other discussion, so the template's name and the displayed text may and should be easily changed if needed.