I suspect you are in a minority, can't back this up with stats though (2.8% etc).
I would be astounded if even one in every thousand players imposed the same sorts of limitations on themselves.
It's kind of ironic to suggest somebody is in a minority because they say they don't board-flip and then attempting to apply the "2.8% meme" when the 2.8% statistic is alleged to be the number of players who DO board-flip regularly.
Frontier's wording implied that they looked at the number of active players in any given day that were board flipping. Since not everyone plays every day and not everyone who board flips does so every day, it's quite likely that the number of players who board-flip is significant, if not a majority.
That said, the exact prevalence is meaningless. If no one board-flipped, or if everyone-board flipped, it wouldn't be a balance issue because everyone would be on the same footing. It's only an issue (from the balance perspective) because some people feel that because they can do it, that they should, while others feel that it's cheating.
The figure is also meaningless from the perspective of Frontier's intended use of the mechanism. They've stated that board flipping was not supposed to be a facet of gameplay.
It's meaningless when discussing the technical merits of unifying the mission servers as well.
About the only argument where it could potentially matter how many people are board flipping is the one that assumes that all those who are board flipping want to continue to be able to do so, which is also not at all clear. Even I compromise my ideal play-style to handle the realities of the game I'm playing and many people have admitted to board flipping in the same post they've said they'd rather it not be possible.