how do you print the reverse reg mark?We use the FC9000... it allows you to print reverse marks... So a big black square with just the reflective showing through as the mark. It's more accurate, but sometimes it does still read wrong.
How often do you cut? If your cutter has issues... Buy a small 3-4" roll of premask, or using 2" masking tape...drop it down over the mark and felt pen it in. I used to do it with a ruler... now I just eyeball it when I have to use our old machine... so long as you dont have the shakiest of hands, it should work close enough to be max a mm or two off.
But just as a reference... We cut probably 150 ft of reflective 680 a month, and another roll or two of nikkalite engineer grade... Maybe 1 in 30 jobs will pickup the mark wrong and cut off... For the others we constantly do 10 FT police wrap cuts with no issues. The 9000's a great machine with its reverse print option... I heard summas used to be better than graphtec... but I think the 9000 has bumped graphtec ahead.