Perf right out of the box may be interesting for some models such as freerides, but not so for other models such as slalom/speed where sailors tend to trim and outfit the boards in order to squeeze out all the possible performances.
I like reading PlancheMag tests in order to have a rough idea, but I don't trust them completely as I see many confused items. I would like them to test all the slalom boards with aftermarket fins. If I was in their shoes, I'd take a range of good fins (Deb SL2 or Elite) to test boards with even fins. Well it would actually take two sets of fins to make head to head comparisons...