I am not sure what you want to know or share in this thread  
 Well, for teaching they are quite sturdy beasts with a good sound.
But in the heat of the action and at gigs shell damage is 
unavoidable. I have mended cracks in a tumba shell 5 times already.
BTW the older models have got quite nice and thick skins which sound fine
even if they are water buffalo.
Dependingon where you are located, those Marathons are quite a good deal.