Actually I would go so far as to say that Next Level has actually tried more plastic balls than I have because to date I have not seen or hit with the Double Fish ABS ball. On the other hand, I tend to obsess more, and do things like weigh them, measure their roundness and such. When plastic balls came out I kind of made it my "mission" to know as much as I could because I was so discouraged by some of the first seamed balls on the market, and also I managed to hit with an early seamless prototype (which was really bad). So this is one of the things in table tennis I know a bit about, plus I follow what other people write about them, including people who have taken trouble to search out the patents etc.
If I write something about Nittaku or D40+ balls, for example on their durability, it is not really guessing. It is because I have had enough experience with these things to actually know (in other words, I don't make comments about products I haven't tried and I know which balls have seams and which ones don't). And durability is like weight. It is something you can know objectively. By the way, I have had nothing good to say about any DHS ball ever marketed before these. Because the stuff they have sold before this is so bad, I was not expecting to be impressed by any ball they sell. But the D40+ is (at the moment) an outstanding product, and I hope it remains that way. So is the Nittaku Premium but about 50% more expensive than it should be.
To be honest, now that the ball situation is settling down a bit, and we have some good options (seamless, Nittaku, D40+ and its clones), I am going to obsess less because the subject is starting to get boring and old. It still annoys me when I see misinformation about 40+ balls out there, but whatever. I should just let it slide now.