@BSN101 The German magazine SURF tested a bunch of alu and carbon booms in 2011. They measured the force needed to pull the boomarms apart.
Force measured in N/mm (higher numbers means a stiffer boom). All booms tested in 180-240 range.
Looking at the numbers the carbon tail of a NP X6 doesn't add any stiffnes compared to other alu booms. Also the cheapest carbon booms are barely stiffer than the stiffest alu booms.
Below are the test result directly from the magazine.
Brand and type of boom / force needed at 10 cm extension / force needed at 44 cm extension
ALU
Aeron OS Slalom / 32 / 25
Aeron V-Grip / 31 / 19
AL360 Ergal / 26 / 22
Gun Expert / 24 / 19
NP X3 / 27 / 22
NP X6 hybrid / 28 / 23
North Sails Gold / 26 / 21
North Sails Silver / 22 / 21
Prolimit Assault V-grip / 31 / 25
Severne Race / 30 / 24
Unifiber Universal / 19 / 17
Unifiber RDG / 18 / 15
CARBON
Gun Select / 35 / 29
Prolimit RDG Team / 39 / 27
Gaastra Blue / 44 / 34
NP X9 / 46 / 39
AL 360 / 60 / 49
North Sails Platinum / 65 / 60
Severne Enigma / 71 / 56