Bill, I think I see why your needles gum up and mine don't--your tape is 5 mils thick and what I use when I sew through it is only 2 mils thick. The 9472LE is the 5 mil stuff I use for structural seams and the 2 mil stuff I use for holding parts in place while sewing is designated as 9471LE. Also, the adhesive type used in your tape is different from that used in mine, so that might also contribute to the difference in needle gumming up.
Incidentally, the reason I use these tapes is the guy at 3M's technical help desk recommended them. I didn't exhaustively quiz him on the differences between the various adhesives, figuring I'd test the tape out myself anyway, and call him back if it didn't work out. So far I've had no reason to call him back.