As Sid as a testing release, not a numbered release, apt-get dist-upgrade on Sid does not require changing sources.list.
From time to time on Sid, an apt-get update && apt-get upgrade will report that something is being held back pending apt-get dist-upgrade.
Running apt-get dist-upgrade will generally update most, if not all, of the items that have been held back.
I haven't bothered to investigate the technical reasons for that, I have just observed that it works. My best guess is that, as updated programs are added to the repos, some of the underlying dependencies do not get updated via apt-get upgrade, but do get updated via apt-get dist-upgrade.
As for Mint and dist-upgrade, as Mint does not support on-line version upgrades, that's a whole nother issue. Anyone who wants to try a "dist-upgrade" on Mint should prepare for it just as if preparing for full new version install, because, if dist-upgrade fails, he or she is on his or her own.
Last edited by frankbell; 08-21-2014 at 08:34 PM.