Having done extensive research on rafter baffles (aka rafter vents, insulation baffles), I have not been able to find any that do not have some drawback to their installation.  In particular, all I have seen call for stapling to the roof deck and are designed to at least partly contact the roof deck for stapling to them.  Does this not sound ignorant of one basic construction fact – that roofing nails are designed and mandated to penetrate the deck up to 1/2″ and thus puncture and/or interfere with their installation?  Moreover, if some or all the roof decking needs replacement after 35 years, it results in damage requiring replacement of the baffles.  Are there not any designed for stapling instead to the rafters, that do not extend to the deck surface?  It seems this would be so much better all-way-around – they would not puncture or tear during insulation and would remain intact if all or part of roof decking were to ever need replacing.