For whats its worth , my motivation to stump up the money for it was as follows :
It seems reasonable Morgan identify 'extras' on the basis of real issues / customer feedback ( as per the recent brace to fix the chassis cracking )
Therefore it follows at some point, regarding the NVH specifically, an issue has occurred requiring extra bracing between the gearbox and bevel box.
My simple brain says , within reason, anything increasing the chassis integrity is a no brainer ( as per the front end brace ) - lets fit it.
Well we all know they are a bit resistant to change, so if they went to the trouble to create this, my thinking is that it is needed.....