I agree and so would my mentor Harry Harpoon, who is a full-time U-blocker. (I reserve my U-blocking just for those pesky high note blow bends.)<major clippage> It is my belief that U blocking is the most advantageous way to high note blow bend.
<more brutal clippage> "How's your high note blow bends?" "Great!" Plays a Jimmy Reed style song. "Wow! What are you doing right?" "I am U blocking like you said. It was uncomfortable for 3 days, then it kicked in!"
I have seen it many times. Michael Rubin Michaelrubinharmonica.com