They are listed as 'neu motors' and the carbon fibre cans are just water cooling jackets.
My guess is they have made an order with neu for a special wind
and that is 'the edge'.
Also, is that hp rating continuous or surge because the neu motor spec chart says a 1521 produces 4.6hp surge whilst the fast elec one is 5hp. Motors are generally more efficient at lower temps aren't they, hence the difference.