The GTS is very fast. I'm biased, obviously, but I know it to be an excellent Cannonball bike.
But I'm still convinced that the GTS is faster than my BV, based on riding instances where I don't believe loading or weight differences were a significant factor.
Oz's comments about his GT should be taken in context: he had a freakishly fast GT, the likes of which have never been seen before or since. He was also carrying much less weight, at least some of which was because I was carrying more gas and tools than he was (ahem). The two things together made for a GT that, in that one specific situation, was very competitive.