All levels???????
Be careful what you read. The seamless balls are better than Nittaku Premium on the following three levels: (1) durability, (2) price, and (3) availability. At the moment there is no doubt about these facts. I may not be selling these balls, but I have played with each of them extensively, with very very large sample sizes, for 19 months. Nittaku Premium do not last as long as seamless on average, they are far more expensive, and for most of the last year they have been very hard to find. I have managed to acquire a pretty good supply by buying as many as various vendors would allow on brief windows of time when they were not back ordered. Often, the limit was four boxes. The costs of shipping I have had to pay have added to the very high price. For months on end, they could not be purchased anywhere, including vendors in Japan. Maybe, this is getting better. We will see.
I personally like the playing properties of Nittaku Premium 40+ the best and I believe they are closest to celluloid (which is why I was willing to pay a super-premium price, plus shipping). But if you look around the web, not everybody shares my opinion that these are the nicest to play with. Some people think they are too hard (like little rocks), and some complain they can't spin them as well. (I completely disagree with the spin comment and can't figure out how it could possibly be true, but for whatever reason, several people are getting that impression-- and they don't like the balls). A lot of your opinion of a Nittaku ball will depend on what you are used to.
So I am just pointing out that vendors do not necessarily have the most accurate information. In this case, TT11, one of the best value vendors in the world, is making a statement that is not true (the part that Nittaku Premimum is better on all levels).