I did not experience that, but the only no wind I have right now is RSG. On hole 14, par 5, the fairway is pretty flat (for RSG). I am using a L71 Nike ball. FTS vs FBS was not drastic, but FBS won by a few yards for me.
In actual play, I generally prefer using 1/2bs -> fbs. How much I tend toward fbs will depend upon several factors. Primarily, I prefer to use greater carry so as to place the ball more precisely for my next shot. Take a course like RSG, with its rolling, and wacky at times, fairways; to send a ball flailing down most of those fairways with fts and allow the fairway to play out like a pachinko game with my ball is not something I would desire. With a stronger headwind, I might acquiesce and try to get under it a bit with a L48 R1. But, though only listed as a med-high club, it still gets up in the wind IME. Plus, catching the face of a bit of rolling fairway can end the resulting roll portion of travel in a hurry; with bs, I can be (reasonably) assured of at least Xyds due to the carry. And with any good bit of tailwind... Weeeeeeeeeee!!!
You are correct: with fts vs fbs, the distance achieved on a (primarily) flat fairway with no wind will typically be nearly identical. This did not used to be the case, as the L48 R1 has... changed... over time. The first week it was out was one of the most riotous I and several of my friends have experienced playing WGT. We regularly got 300yd+ drives by utilizing 2/3 -> fbs; using no spin or, gasp, top spin, was unheard of. Even into a 21mph headwind on STA or RSG; those would simply mean backing off the bs a little, because to top it would result in a crap shoot, and a shorter result. A few weeks later though, "the change" began.