I initially rode the 1600, but bought the 1700. I did notice a difference, no it wasn't the difference between a moped and a Busa, but it was noticeable. I also have to admit, I've never ridden a BB kit bike, so can't compare the 2, but I can't come up with any logical reason why Triumph would use a different cam in the factory 1700 vs the BB 1700 kit. Not saying they don't, but without knowing more about the marketing aspect of the kit, I can't understand it. If it were hotter, I'd think they would sell the BB kit cam as a performance upgrade for the stock 1700 (maybe they do and I just haven't seen it). Unless I it was from an "official" source, I don't know how much is truth, how much is salesmanship and how much is just people wanting to think they have something better than the next guy. I would be interested to know if it was true.
Better living through chemistry.