As a member of the devguide target audience, I think for this the devguide should give alternatives with brief pluses and minuses. After importing and applying a patch to the earliest applicable 2.x or 3.x, move it to the other series with graft (new, possible better merge,possible problem with case or series specific changes); re-import (possible loss of local edits); or even export/import (keep local changes, no case problems). Expanded, the previous sentence should only be 10 or at most 15 lines. Then each person can pick the method that works best for them, which might not always be the same method for each patch. In a few years, this topic will be obsolete except for security issues.