Where you wrote:
...Unfortunately, for better or worse, DC is an eclectic place and it's hard (for me at least) to figure out ways to substantially reduce the clutter without causing real harm.
"Clutter" might not necessarily be the correct term, if it is referring to forum content.
What DCF currently seems to be could be regarded as not just a CMS, but rather a self-contained treasure-trove - a valuable/useful "knowledge base" - consisting of various content - including discussions which, in many cases, lead to improved definition of the knowledge documented.
This point is perhaps best appreciated when, during a discussion on (say) "SubjectX"
, some research using the (rather kludgy) forum search function or (better) a search using <site:donationcoder.com/forum/ SubjectX> can rapidly turn up relevant links within the forum and which can then be sifted through to see what's new/old information to help better-inform the discussion.
Once I decided that I might be able to contribute something that could be useful - for myself and to the forum - I started doing the various "Mini-Reviews" of different software, so that relevant new
knowledge could be related/attached - which is why I update the reviews with cross-posts to the relevant post/comment where someone has made a fragmentary post/comment about the same subject as the review.
What I effectively did there was make a unilateral decision to assume the role of a kind of unofficial curator - i.e., having created a review, I would then try to keep it current, updating the review from time to time, with new/additional knowledge relevant to the software being reviewed.
I did this deliberately, because I saw how some really quite good/useful
reviews had been done by forum members in the past, but many of these seemed to just peter out with the passage of time, sometimes starting up years later in a separate, disconnected thread with people attempting to re-invent wheels. I'm not saying that there should
have been, but there was no implicit discipline
upon the authors (or the admins) to keep the things they wrote about updated/consolidated and relatively current - which seemed potentially a great waste, to me. If there is any "clutter", then I suspect that that is where the clutter lies - i.e., as fragmented bits of seemingly unconnected knowledge scattered across the knowledge base - but these bits of knowledge may well be relevant to each other and could be usefully interconnected if there was a librarian involved, using some kind of artificial framework of reference - e.g., a structured taxonomy (scheme of classification).
The question then might well be"What sort of taxonomy?", but I don't have the answer, though I do have some thoughts on it.
Returning to the OP, therefore, I suspect that "Modern forum software" isn't the issue/problem - in fact it probably isn't an issue/problem at all. The real issue might be better phrased as (say) "addressing what the requirements are for this forum in the future, given that where we have arrived at today is arguably a self-contained treasure-trove - a valuable/useful 'knowledge base' ".
However, it might be that, on reflection, the general consensus is that this base is not actually as valuable as one might have argued, and it should therefore (say) be scrubbed clean of detritus/clutter and a fresh, modern, new and empty CMS implemented with a provisional index to the historical and static archive of the old content - i.e., no "halfway house".