I've had it about a year, don't remember specifics. It was about 3.5" across when I got it, and it's about 5.5" across now. Pitcher size has increased dramatically, though. Considering how many of my other plants have grown in less time, I'd classify this is a slow growing species, but not as slow as lowii or macrophylla.
As for the release of this hybrid from BE: I don't know what the big mystery is. I mean, when you grow plants from seed (and this is especially true of Nepenthes, from what I've seen) there will be some that get large, fast. And there will be many that grow at a similar pace, and then there will be plenty of late starters and slow developers. Some plants may be 2" across in little more than a year, while some will take three times that to reach the same diameter. So this is what we see when a grower makes multiple "releases" of a species: those shipped three years after the first batch are the late bloomers, which just took longer to reach a marketable size. There is no mystery; these are almost certainly from the same seed lot, the same sowing.