They are curious indeed. I've never had issues with varying numbers, because for the most part they are usefull within one company and within one plastic type. From there on you can extrapolate what to expect from what disc.Flight numbers are such a curious thing, especially High Speed Turn/Stability, because there's no world in which I'd classify a Sword as a -2 unless it was well-seasoned (Swords are my primary DD and I've seen the difference between me throwing them, ~350-380, and bigger arms, 400-500).
It's been a few years since I've thrown a Giant or World, so I can't speak to them but I've primarily a Westside thrower and I disagree strongly that the Prince is redundant in their lineup
The problem, however, is that most people look at them universally and use the OG Innova as the benchmark. Now when you compare the Sword to something like -2 Shryke, based on my experience after two weeks of use the Shryke is more stable than Sword and that is an issue.
I'm also curious how you can say that Prince is not redundant when you don't know the discs that it's being compared to. Even after watching some reviews, I really don't know how if differs from Giant for example.