I did a head to head test (pun intended) of the floss action brush head against the traditional Oral-B head.
The difference between the two heads is that the floss action one is slightly larger, and has yellow rubbery cleaning elements as well as the usual bristle.
After each test I flossed to see how much the brushes had left behind.
Now, a single test of each head is pretty unscientific. A statistician would want dozens of tests before drawing a conclusion, but one is enough for me.
And the result? Floss action really works - it gets right in there and hauls out more plaque and almond fragments than the standard bristle head.
For me, that makes it worth the extra cost.