Yes they are good rubbers, very good in reality.
I play since a few month with the National V blue sponge. Before that I played with the G20 and before the G20 I played with the VIP 2018. They are all very good rubbers for whom like Chinese rubbers. They are cheap and last very long. In fact the sponge is used before the topsheet. The topsheet of the VIP and the G20 are different from everything that already exists. They are stripped, in one way for the VIP and 2 ways for the G20. The grip of all those rubbers is enormous. The G20 have the highest throw a little bit further comes the National V and after that the VIP.
The National V has a gigantic dwell time, the sponge is hard and need to be boosted. The topsheet is soft and elastic in contrary of the VIP and the G20. The amount of spin you can impart is very high. They are cheap rubbers and some can be afraid of the quality but don’t need to be.
It exists also a rubber named G10 to compete with D09C for half the price.
And too they have a large choice, for some of us it may be too much to see clearly their range, of rubbers for decent prices and more that that if I can say so.
Tuttle and Kokutaku is the same brand/factory in fact.