Actually, if the new UA sizers are used (my next trip is on United), then the B&R U116 could not be considered as a personal item, since the personal item dimensions are 9" x 10" x 17" while the B&R U116 dimensions are 8.3" x 12.5" x 15.5". So, the width is 2.5" too big.
Too bad. I really liked this approach but I guess it may not work.