You won’t know which resin is better for you till you actually try it, it’ll come down to which you believe has better workability.
No amount of spec reading will help with that.
Whether it be Akemi Polysoft or Tennax.
No polyester resin will actually bond porcelain in the true sense of the term.
It has to be a full blown epoxy resin, which is another beast altogether.
Polyester resins are ok for soft applications, which is what this is.
You don’t need a full blown epoxy resin for what you are doing.
Americans swear by Silicon, based on the fact they feel that if there is movement, the Silicon will cope.
Polyester resin can split in this scenario.
Like I said, different resins, different applications.