Post-hoc update: we were able to capture a bit more than we thought we would - namely, drafts. Final summary of the changes follows.
Both of these should conform to the reply we received from IETF.
In total, 18k posts on Stack Overflow were fixed, and another 7k network-wide.
Yaakov has my sincere gratitude for helping get the tooling for this up to date and effective to make this network-wide change easy and fast - and the tools should be more enduring for future use cases as a result, too.
I will be waiting a couple days after this post to make these changes, to allow for some feedback on whether my plan is the appropriate way to proceed for our network. If you have any reason you think we should pause or change course, speak now or forever hold your peace. If nothing comes up, expect this to be done by end of week.
I've spent some time chatting by email with a very helpful contact at the IETF, and I'm grateful for their several quick replies. Here's the long & short of it.
rfc-editor.org is the canonical location for RFC documents, and will remain the correct destination for now. The RFC document locations at the various IETF URLs aren't canonical repositories, even though they do ultimately point to the same documents. I gather (but could be wrong) that these are more so 'working repositories' than the reference documents themselves.
After RFC8650, the format for RFC documents changed, and there are some visual differences between
datatracker.ietf.org. Our contact at the IETF has indicated that there shouldn't be any differences in the content between the two - but one is a canonical resource, and will have different formatting for pre-RFC8650 documents. As an example, see:
Since I'd personally prefer we reference the canonical documents for the longevity of the posts on our network, my plan is to move both
https://tools.ietf.org/html/[RFC####].html over to
https://www.rfc-editor.org/rfc/[RFC####].html, which is the primary resource for published documents.
- Links targeting
http://tools.ietf.org/html/draft-*, where RFC internet drafts were stored, may need to be moved to the IETF data tracker - and this will need to be double checked by hand.
- IETF may move these documents in the future, and though we can expect a redirect for these documents, the possibility we'll need to move these links over in the future is not precluded.