@Lanthanide: I see your point. MW talk pages can be threaded, if participants in the discussion manually indent their comments -- but unlike SEN's system, it requires manual effort on the part of each poster. (You can indent a line of text in a MW page by prefixing it with ":".) On the other hand, a much wider range of formatting is available compared to SEN's wiki's talk pages (where I can't seem to get even a line break to work).
(I'm surprised that I'm not being shouted at right now. I figured that the fact that SEN has its own wiki system meant that everyone here loved it and wouldn't trade it for
legitimate SCII beta access the world no matter what, and that's why it's been kept. I was actually a little worried when I posted earlier.)
Here are the key(est) concerns regarding any potential switch to MediaWiki. (If the admins wish to consider this idea, but don't feel like doing a ton of Googling.)
More formatting, including (nerf'd) raw HTML and (inline) CSS. Means we can present information more efficiently, but it also steepens the learning curve.
On-wiki images. MediaWiki allows users to easily upload images, and makes it easy for sysops to manage them. No more broken images!
Templates. MediaWiki offers the ultimate way to reuse wiki formatting. Templates are pieces of wikimarkup (technically, they're full pages) that can accept parameters, perform simple logic, and be included on pages. This, combined with the ability to use raw (nerf'd) HTML and CSS in pages, makes it easy to create flexible and reusable widgets, like Wikipedia's infoboxes. The code for invoking a template is very short, too (
{{Template name|parameter|parameter}}). (Try to imagine how much space and time it would save if, for example, a template were used for units in
Unit Information. We would just call the template, pass it the stats, and it would format each unit for us. A ton of massive table row codes simplified to a couple curly braces, pipes, words, and numbers. Beautiful.)
And here's where things go a little bit downhill.
No (default) integration with SEN's user database. It
might be possible to get the wiki to share user databases with SEN, but I would have no idea how to do such a thing, or if it actually is possible.
Categories are more flexible but less manageable. For example, on MediaWiki, to delete a category, you have to de-categorize its members. (And if someone edited the category (because yes, categories can be pages, too), then you have to get a sysop to delete the category page afterward.)
There's a ton of formatting, making it easier for users to format articles inconsistently. Most wikis have a "Manual of Style" to combat this. (The one used by
Halopedia is especially good, in that it includes standards for different types of articles (characters, weapons, etc.) and even has copies of each article type's infobox.)
None.