I respectfully disagree with John K. I think the interesting thing about this test is exactly the fact that they are testing different gears which seem reasonable to me. You most likely won't put a 11m2 race sail on a freeride board, thus, having same sail wouldn't make much sense. They have put together rig+boards which one would actually think of buying.
The riders have been the same, and that is what makes it so interesting as well. Same guy testing different board+rig in same place and condition.
I wouldn't have believed it myself, but Surf Magazine usually is quite accurate on their tests. And the figures are there to prove it.
If nothing else it is at least an eye opener to test different gears before deciding on what to get. I fortunately can have 2 boards, thus, I might consider a freeride + early planning sail for light wind. Once it gets above 14knots I switch to smaller board and different sail.