Hi, thanks to everyone.
The material is fiberrod, I have to say that compared to the other resins it is the most similar to hard rubber, both in sound and feel.
I don't know exactly the differencies between the slant sig 1 and 2, I will ask Theo about it.
@tryptykon the mouthpiece responds very different to different reeds and ligatures so I think you could go to a store and swap ligs and reeds to find the "right spot".
I would like to try a 7 with a harder reed, it could be an interesting match.
I usally play on the ambika 8 that is a bit darker and less midrangy, but I can hear "Theo's touch" on both mouthpieces.