The David Mackay Brown website states that his RoundAction SxS Double Reciever "is without doubt the strongest of designs."

I dont know enough about SxS rifle designs at this stage to know what makes it stronger than any other SxS breakopen rifle. Can someone Knowledgeable tell me what makes it stronger or the strongest as claimed?
Surely he is only refering to break open actions and not including the Hoenig rotary or Hagn fallingBlockSxS.