A quick note to tell you that I have tried to look for examples of breakage due to how mtime preservation is currently implemented in portage. Unfortunately I didn't find anything, maybe because I'm not knowledgeable enough or because I can't afford to spend any more time on this. If any of you can provide an example then please do so.
In case nobody could show any sign of such breakage I would have to add to the list of two propositions to vote on: 3- Do nothing. We can always point to code that shows the implementation is suboptimal but we have to understand that some of us who are less proactive at fixing issues may want to procrastinate until breakage actually happens. Denis.